The Value Proposition in Audio: It's Not Your Father's Class D

THE VALUE PROPOSITION IN AUDIO: IT’S NOT YOUR FATHER’S CLASS D!

The latest and greatest in microelectronics for audio – value is up and cost is down

INTRODUCTION

The new wave has come ashore, and it’s washed up some fine bits for audiophiles.  As we haven’t yet looked in depth at the latest little joys, I thought a review of the market, historical perspective, and some of my impressions of the newest stuff would be helpful.  It’s impossible to discuss this without including the huge role of the Chinese and the increasingly strong supply side from many other countries around the world.  Taiwan, Vietnam, Denmark, Germany and many other countries including the US are now integral to the world of digital audio and class D amplification (which are not synonymous).  Cool stuff is coming from everywhere!!

THE GARDEN OF EDEN

It was the summer of 1959, and Motorola was the king of consumer electronics.  My birthday was coming up and I knew I’d be getting enough cash to buy the one thing a budding young musician couldn’t live without – a transistor radio small enough to fit in my pocket so I could listen to music anywhere.  Motorola had just announced the X11, and I was in love.  I got it and it never left my side.

What I didn’t know at the time and for years afterward was that this was the first major incursion of Asian electronics into a major American market through a major American manufacturer.  It was probably the first concession by a giant American company that the future was in outsourcing products to foreign manufacturers, and here’s the real statement of origin of my beloved X11:

To be honest, it was an excellent device.  It survived the rigors of carriage in a teenager’s pocket for several years, and I learned many tunes for my band from it.  Sound quality was less than stellar, but its output was clearly audible and understandable.   And best of all, I could afford it at $29.95 (which would be $304.90 in today’s dollars).  The X11 was entering a market with serious competition.  The Zenith Royal 500 was probably the cream of the crop – bigger (and unable to fit in a shirt pocket), with better sound, more power, and a much more robust construction.  It as made of nylon rather than flimsy plastic and was hand wired using the best American components, starting with transistors from Sylvania, Raytheon, and TI.  The Royal 500 cost $75 ($763.50 in today’s dollars!) when it was introduced in 1955.  RCA, Philco, GE, and Sony made competing radios but the Zenith was king…...for 4 years.  Motorola’s $30 X11 was a game changer in many ways, starting with Zenith’s reduction of the price of the 500 in 1958 in anticipation of the X11 ,and their introduction of the Royal 50 for the same price as the X11 in 1960.  The first Royal 50s were also made in the USA, and Zenith apparently lost a lot of money on them.  They finally threw in the towel in 1966 and shifted production of pocket radios to Asia.

Why am I telling you this?  It’s the same old story ever since the world began:  opportunity makes strange bedfellows.  And, as Paul Newman’s character Harper said in the movie of the same name (and one of my all time favorites), “cream and bastards rise”.  Fortunately for us, there seems to be enough cream in the modern world of audio equipment to make us happy despite the bastards out there who try hard to take our money for shoddy goods with poor after-sale support and high failure rates.

At 13, I already knew enough to recognize some of the trade-offs I was making in buying a $30 radio I could afford vs saving for a year to get the Zenith 500 I really wanted.  To be honest, my family and I actually believed that I was getting a “real” Motorola product – we were entirely unaware that I actually bought a Tokai product built well but to lesser standards.  Performance was adequate for my needs, but it was no Zenith.  I opened it many times over the years and do not recall ever seeing any indication that it was not made by Motorola.  Google was no help, and here’s the only label I ever saw:

For much of my childhood and teenage years, “made in Japan” was a four letter word that was often appropriate.  The high end of Japanese audio was there, but we didn’t know it and they apparently made no effort to bring it to us.  Luxman was founded in 1925 and was a pioneer in top quality audio components long before most American companies offered anything that could have competed with the best from Luxman.

FAST FORWARD

“Everything’s made in China now” is more than a cliché – it’s closer to being true than it probably should be, especially after our current / recent supply chain delays and an increasingly unpleasant relationship between the US and China.  It’s generally been true in my experience that early Chinese audio electronics were substandard in quality, performance, and support.  As a result, they were not great value despite their low prices.  Between the marginal performance and the high failure rate with little hope of obtaining repair or replacement, buying Chinese was most often an adventure and a learning experience.

But the Chinese audio industry caught up with current standards a lot faster than early Asian car and home appliance makers did.  I think it’s fair to say that there are some excellent Chinese audio electronics now, and their high levels of quality and performance make them good values.  Support is still not up to the level of the better manufacturers in the West, but it’s getting better.  And competition from Taiwan, Vietnam et al has pushed the Chinese a bit to up their game.  But much of the leap in product quality and sophistication out of China was stimulated by western influence and education.

This may well have started with the emergence of major Chinese audio manufacturing facilities that were closely overseen by the western designers and engineers behind pioneering global brands like Emotiva and Prima Luna.  A few western audio companies (e.g. iFi) claim to own their own factories in China, which I always thought was impossible without joint participation of a Chinese entity.  According to the law firm of Harris | Bricken, which declares itself to be expert in international business law and Chinese manufacturing:

“No American or European or Australian company (or any other non-Chinese company) can own a Chinese factory directly. It is possible the American or European or Australian company that claims to own a Chinese factory owns a Chinese company (a WFOE [wholly foreign owned enterprise] or a China Joint Venture) that in turn owns a Chinese factory, but the odds of this are incredibly slim. None of my law firm’s international manufacturing lawyers have ever encountered a foreign company that owns a Chinese company that owns a Chinese factory that does contract manufacturing for third party companies. Something like this is possible, but it is exceedingly rare simply because third party manufacturing is nearly always a complicated, localized and low margin business.”

Like most of you, I own equipment from Emotiva, Prima Luna, iFi and other western sources who manufacture in China.  The quality is excellent and I’ve had nothing but great service from such products since my first Emotiva piece purchased years ago.  The only problems I’ve had with any of these were a failure of the USB controller chip in my Emotiva Stealth DC-1 at about 5 years (replaced free of charge by Emotiva and turned around in a week) and a software anomaly in an iFi DAC that caused it to drop the USB connection when it was powered down.  I contacted ifi within a week of purchase, and they were both uninterested and unresponsive to my requests for help.

They claimed that the DAC was not intended for use with Linux.  When I sent them a copy of their own web page saying that it was fine with Linux, they punted and never did make any effort to fix it.  This was a failure of their own workforce from designers and engineers to customer service staff and management.  I swore I’d never buy another iFi product and I never have – but it’s absolutely not because they’re made in China.  The hardware is of high quality, but the value is lacking because it has a software glitch that they won’t correct despite the ease of patching the firmware.

Service from western companies for the Chinese made products in their portfolios is generally excellent, at least for me.  In addition to Emotiva’s amazing service and customer relationship management,  Kevin Deal’s Upscale Audio has been very responsive to my questions and requests.  My Prima Luna power amplifier lost a channel well out of warranty, and Kevin set me up with a tech on the east coast to minimize my shipping costs.  He also paid half of the repair bill, which he did not have to do.  The problem was just a bad solder joint, and the amp remains perfect today almost a decade later.

The sound quality of my Chinese audio products from WFOEs or China Joint Ventures is uniformly excellent +.  My Prima Luna power amp sounds glorious, and the Stealth is still the workhorse DAC in my recording setup despite the presence of several newer and “better” DACs (including an SMSL, the first Chinese audio product I bought from a Chinese company and about which there will be more further on in this piece).

Sound quality from my 100% Chinese products is also excellent, although I’ve had a few pieces that didn’t live up to their hype or my expectations.

Before we get to the nuts and bolts, I think a disclaimer is appropriate.  I am not yet recommending Chinese audio equipment as direct replacements or substitutes for the wonderful items we get now from so many makers around the world.  The level of quality and support from our favorite makers in the US, Europe, Scandinavia etc remains consistently higher than the level we get from many Chinese makers in much of their audio equipment.  My main systems are still main stream – PrimaLuna, Focal, iFi, Thorens, Emotiva, JBL, Edifier etc.  But I’m now using a few Chinese pieces for daily listening, and I’m very impressed.  If the quality holds up, I’ll be trying more.

I have needed support a few times because things either arrived with problems or failed while infants.  One of my Chinese amplifiers has started putting a clearly audible hum through the speakers for the first 3 or 4 seconds after turning it on - and there is absolutely nowhere to get support.  Amazon refers me to the manufacturer, and they tell me to submit a request through the Amazon website.  It’s a few weeks past the period for return, so I’m living with it because it goes away after a few seconds and the amp sounds fantastic.

Be aware that this is not uncommon with Chinese audio equipment right now – I’ve been there before and am living with a few problems.  Fortunately, the stuff costs so little that I accept it as educational and disposable – after all, it’s all part of my quest for value in audio.  But the situation will have to be addressed before the Chinese audio industry can be taken seriously as equals with global high end audio competitors and their products can be comfortably purchased for routine use.

WHY BOTHER?  I ALREADY HAVE A WORLD OF GREAT STUFF AVAILABLE TO ME!

These little devices can fill roles you didn’t know you had available.  Most modern computers have BT on the MOBO.  Wouldn’t it be great to have a cheap little amp and speaker set you could use for video calls etc so you wouldn’t have to bother with your main computer audio setup?  How about a tiny system you could leave in your office and lock in a desk drawer when you’re not there?

Want to start your kids on the road to audio fulfillment?  Make them a small and inexpensive but powerful system with good SQ and simple controls.  Let them pick and assemble it with you to give them a technical experience and form good habits.

Make your spouse or SO happy by getting the system that Rube Goldberg built for you when you were in college out of the living room and replacing it with unobtrusive, cute little components that you can control remotely with tiny little remotes you keep in the coffee table drawer.  There are MC class D amps out there for home theater use, and many of the stereo units have a separate sub output so you can hook them up to your big screen TV and surprise the family with great theater sound.

Downsizing?  Free up space in your new condo by placing that 10.1 home theater monster with a sleek little class D powerhouse and wireless MC setup. Live a little!!

NUTS AND BOLTS

The heart of the tiny amplifiers pumping up excitement among audiophiles is the class D amplifier chip.  And they’re not all Chinese!  Per the UN, the leading produces of chips around the world are China (which includes Hong Kong and Macao), South Korea, Singapore, Malaysia, the United States, Japan, Germany, the Philippines, the Netherlands, and Thailand.

The competition is fierce and the products are getting better by the day.  With some hope that the recently passed legislation aimed at supporting a renewed American chip design and production effort will float the audio boat as well as the automotive fleet, I strongly believe that the IC is poised to become one of the best examples of global development and cooperation after years of being dependent on China and Taiwan for most.

The best audio amplifier chips come from a few sources in Asia, but some of the world leaders in quality and value in class D chips are western.  Infineon is in Munich.  Hypex is in the Netherlands.  Qualcomm is in San Diego.  TI is still headquartered in Dallas, TX although they manufacture at more than a dozen sites around the world.  Comparing all of these chips is enough work for multiple authors to generate multiple publications, and new variants come out so often that by the time one is tested it’s often already been sunsetted.

I’m going to describe my experience with two very different Chinese class D amplifiers.  Both are tiny stereo integrateds with a variety of analog and digital inputs, both are rated at 100W RMS, both sound great, and both are inexpensive although one gives that term new meaning.

The Pyle PDA29BU.6 was $33!  It’s a typical Chinese audio product directed at the American market – it does too many things for my taste, although it seems to do them much better than would have been the case when each function was in a discrete component set.  Chips have finally made multi-functionality practical and reliable, even if somewhat awkward because all of the controls are within multi-function soft switches, knobs and buttons.  It has a preamp that will handle microphone and musical instrument inputs through two ¼” mic inputs.  Other input sources include SD card and USB stick, BT 4.2, RCA line level inputs, and an FM tuner (!) all integrated into a 6x7x2.5” box with miniature rack handles at each end of the face plate.

I am also evaluating the Pyle for live performance with electric guitars, keyboards etc.  As an old and aging professional musician, I’m always on the lookout for smaller, lighter, better electronics.  My current regular gigging amplifier is a Henriksen Blu 6, which is a 120W class D unit (ICE powered) with a 6.5” speaker plus a fluid-cooled tweeter in a 12 pound, 9” cube.  The Blu is the gold standard for working jazz guitarists – it sounds fantastic, looks gorgeous, is made as well as can be, and is built in Colorado.  I also have a 45 watt Quilter class D pedal amplifier the size of a pack of cigarettes and a Quilter Superblock US that’s the size of a paperback book, sounds gorgeous, and puts out the equivalent power of any 25 watt tube amp in the world.  The Quilters are just amplifiers (ie no speakers).  I play them through the latest in small, light speakers for musical instrument sound reinforcement – Toobs.  I have a 10” Toob with a Jensen Tornado speaker with a neodymium magnet plus a pair of 6/5” Toob Metros with SICA drivers.

The other (a Douk ST-01) was a whopping $129 and has a vacuum tube front end!  It comes with 6J5s in it, but you can use 6J1, 6J4, GE5654, 6AK5, 6Ж1n-EB and other similar tubes to fine tune sound character.

Let’s discuss the Douk first, because it’s an audiophile product.   Just for information, since I can’t find any comparison tests of the chips themselves and I’m not equipped to do any meaningful lab testing myself, the power chip is a TI TPA3251. Before buying something like this, a web search is in order.  Let’s start with the specs for the TI chip (which is now a 6 year old design bettered by the latest from ICE, Hypex, Infineon, and TI itself):

The jump in THD across the last 35 watts of rated output is typical of these modules and not at all relevant to real world listening.  The specs at the bottom of the chart above are the most important and reflect the high quality of the real world listening experience.  If you’re trying to push low impedance, highly reactive loads to insanely high SPLs with these devices, you need emotional support.  Maybe a future generation will do it well, but even the latest class D chips are simply not (yet) designed and built for commercial sound reinforcement or concert hall realism from highly inefficient speakers.

The comments on audiophile sites are quite informative, and the preponderance of sentiment is at least 4:1 in favor.  Here are typical comments:

• “I use a Nobsound amp. The MS-10d. It's only a hybrid. But uses tube in the preamp stage. I have to say. I did a svetlana / wing-c tube swap on it. And I'm quite pleased. It's almost laughable as I'm using it with a Rega RP-6 and Monitor Audio Silver 8s. It's by far the cheapest part of my system. The DAC I use on my CD player cost more. But it never disappoints, it's rated 25x2 watts is more than capable, and has no issue with the 4ohm MA 8s. The sound is warm, but not overly so, sweet, and conveys every detail my Rega can pull out of the vinyl.”
• “Audiophiles shy away from discussing the Chinese amps. Certainly quality varies, but it's my belief that some offer a lot of bang for the buck. I've owned a Qinpu headphone amp for a few years and have been very pleased with it. I've seen some favorable reviews on the Nobsound amp. A tube swap can be the ticket to pleasing sound on some of these units.”
• “Actually the Ming da transformers are very good indeed as are their amps. One Chinese company worth the money IMO.”
• “This little amp has a huge amount of punch and is really fun to look at, with the vacuum tubes and the VU meter. Contrary to the manufacturer's description, my unit did NOT use the TI TPA3221 chip, it actually had the superior TPA3251 audiophile class-D chip. I know this because I have an engineering background and opened up the unit and took a look inside (see pictures). Construction and internal components are high quality, with 105C (not 85C) electrolytic capacitors and good multilayer PCB's. It's also really practical, with Bluetooth, USB, RCA, coax and optical inputs. AND A REMOTE! I was impressed with the sound quality, low noise and low startup and shutdown pop. It does not have any clicks or noises when switching inputs or setting volume with the remote. The only quibble I have is that they call this a "200W" amp, even though the max unclipped power you can get out of the included 24V power supply brick would be 36W into 8 Ohms or 72W into 4 Ohms. Still, 72 REAL Watts is plenty of power for a bookshelf or even a home stereo system unless you really need wall shaking volumes. I'm really happy with this purchase!”
• “This little amp has a huge amount of punch and is really fun to look at, with the vacuum tubes and the VU meter. Contrary to the manufacturer's description, my unit did NOT use the TI TPA3221 chip, it actually had the superior TPA3251 audiophile class-D chip. I know this because I have an engineering background and opened up the unit and took a look inside (see pictures). Construction and internal components are high quality, with 105C (not 85C) electrolytic capacitors and good multilayer PCB's. It's also really practical, with Bluetooth, USB, RCA, coax and optical inputs. AND A REMOTE! I was impressed with the sound quality, low noise and low startup and shutdown pop. It does not have any clicks or noises when switching inputs or setting volume with the remote. The only quibble I have is that they call this a "200W" amp, even though the max unclipped power you can get out of the included 24V power supply brick would be 36W into 8 Ohms or 72W into 4 Ohms. Still, 72 REAL Watts is plenty of power for a bookshelf or even a home stereo system unless you really need wall shaking volumes. I'm really happy with this purchase!”
• “This is AUDIOPHILE-quality good! Amazing soundstage, musicality, and detail.While it might be easy to dismiss this is as a toy, rest assured that this is one of the BEST budget amps I have heard. Paired with the Sony SS-CS5 bookshelf speakers, this combo packs an unbelievable value for systems under $500. The resolution, detail, warmth, image, and soundstage are VERY impressive.First, I connected this amp to my reference system (Zu Adio DW Omen II speakers, Denafrips Ares II DAC) temporarily replacing an A50 MKII 300B tube amp, and was quite surprised at the quality of the sound. I listen mainly to classical, choral, and acoustic jazz, so imaging and soundstage are very important to me. There was an amazing amount of air and separation among the instruments, and vocals sounded very sweet (harmonically rich) while still retaining great definition. This little amp has enough character that it thrives in a refined system. However, the REAL surprise was when I integrated into a more price-appropriate setup with the Sony CS5's. These budget speakers are an amazing deal themselves, and there is a great synergy between this amp and speakers. (Mind you, it sounded good with the KEF Q150's as well, but the CS-5's were a perfect match.) At regular price, you can put this system together for under $300 and it will easily outperform almost anything in that price range. You are getting a great amp, a tube preamp, a very decent DAC with optical, coax, and USB inputs, plus Bluetooth, plus a REMOTE, and a line-out for a subwoofer! That's a tremendous value. Also, I tested the internal DAC with the optical and coax inputs and it was surprisingly good. Not quite at the level of the Denfrips ($800 DAC) but very close. This is just not a great amp/DAC/tube combo for its price-- it's a great piece of gear, PERIOD. Highly recommended.”

OK – I think you get the point.  Up front, I can state clearly that I agree with the raves.  I’m currently driving my Focal 726 towers with the AT-01 in our open living / dining room space, which is about 25’ wide and 30’ long.  The default amp in that system is my Prima Luna Prologue Premium, so the sound quality is excellent.  And it’s not that far behind with the Douk in the power position.  Bass is amazingly deep and tight.  Mids are a bit leaner, only slightly veiled, and essentially uncolored.  The top end is clean and clear without being shrill.  I actually love it!  If you want great sound in a user friendly integrated amplifier with a more-than-decent preamp that will accept multiple input sources and modalities for $129, this is definitely it!!

I have no trouble generating clean SPLs with big band and large scale classical recordings that average 80-85 dB with peaks above 95.  The sound is not at all fatiguing, and there’s enough headroom to obviate compression of peaks on any program material as long as you keep the average level at or below 85 dB.  This little sucker is LOUD!

OK, you say – but what about the integral DAC?  Is it even listenable?  I think it’s much better than that, and so do most of those who’ve posted reviews online.  Here’s a typical comment about Douk DAC and preamp sound quality:

• “The more I used [it], the more I liked the sound. One or both of us went through a break-in period. Perhaps the tubes settled in and improved. Perhaps I simply adjusted to the sound. Either way, [it] grew on me.  I swear the clarity has improved dramatically. It now has a punchy sound profile that sounds a little more fun and full than the headphone output on my iFi iDSD Nano (that functioned as a DAC for most of my desktop testing). I no longer perceive a lack of clarity or veil over the music, and [it] has a reasonably quiet background with minimal hiss perceived on a silent input with regular full-sized headphones.”

I also have an iFi DSD Nano.  I have to say that the DAC in the Douk ST-01 is a fair match for the iFi (except for resolution capability – the iFi does DSD but the Douk does not).  I also think that the DAC in the Douk is not far behind my SMSL for sound quality.  The Douk has a slightly lean midrange compared to the SMSL set to the filter(s) I prefer.  But I could enjoy this as my daily listening system, and I’m doing that right now as I continue these evaluations.  Here’s the rack under our grand piano in the living room right now:

You may ask about the array of inputs on the Douk.  I was planning to ignore them until I couldn’t resist trying them all.  So I connected the audio output from our big TV to the Douk, along with a Chromecast Audio, the USB output from a Raspberry Pi Roon renderer, and the Bluetooth output from one of my PCs running Roon.  All I can say is that the little Douk is good enough to reveal the deficiencies in suboptimal sources.  The integral Bluetooth (4, I presume) sounds a bit dull and lacks the “living color” of even a high quality 44.1 or 48 digital audio file from Roon.  Bass is not as tight and the highs are thin.

The analog inputs (RCA) are fine.  I tried the analog output from my Parasound preamp/DAC through the Douk and was very pleasantly surprised at the smooth and cohesive sound I got from good vinyl played on my Thorens TD125 / SME / Audioquest ‘table through the Parasound.  Analog audio out from the Samsung TV on the wall is what you’d expect – the optical output sounds a lot better, but then I couldn’t leave the Chromecast connected to the single optical input.

Lest I forget, it also has a dedicated line level subwoofer output (RCA).  I connected it to my little Yamaha 8” sub, and it’s truly excellent!  Bass is amazingly tight and deep, with no extraneous noise at all.  There’s absolutely no audible hum from the Douk after about 2 seconds of very low level hum on powering up.

The remote is also much more enjoyable and useful than I first thought it’d be.  First and foremost, it works very very well and hasn’t yet failed to prompt the desired response on the first push of a button.  Yes, it’s a flimsy plastic one - but the buttons themselves feel better than the ordinary cheapos.  When I got my SMSL SU8, I bought a spare remote because I figured I’d never be able to buy one in the future if I needed it.  Maybe I should do the same for the Douk, but I can’t find a source.

So in summary, the Douk ST-01 is a very nice integrated class D amplifier that provides excellent sound quality from multiple sources from a tiny box.  It has a vacuum tube front end that actually does sound rich and warm – it’s light years ahead of the prior generation of dirt  cheap imported amplifiers.  I could live with this as my only amplifier if that were necessary.  In fact, from the experiences I’ve had so far, I’d say that this is my first choice for the heart of a low cost audio system that will drive equally good and inexpensive passive speakers to higher SPLs than most of us would ever need from all kinds of devices through analog and digital inputs.  The only things it really lacks (if you need them) are a phono input stage and a headphone driver.

I dug back a bit to find info on the pre-class D Douk amplifiers and found some useful impressions of their earlier 6.5 WPC tube amplifier, to wit:

“The first and most obvious appeal to the Chinese brands, this case Douk Audio is the price point. You will not touch even a used working tube amp from one of the big manufactures such as Dynaco or McIntosh for anything close to the price of one of these. That is not to compare them at all, however if you are new to tubes and not sure where to start the cost of entry starting usually well into the thousands can be off putting. I have listened to both McIntosh and Dynacos in person and they are incredible, if you have the money you will not be disappointed, though for the money Douk Audio is surprisingly pleasant as well.”

And it is, indeed, surprisingly pleasant.  Add to that the clean and high quality sound from a current class D amplifier chip and you have the beginning of a new era in audiophile value.

OK -$125 NOW BUYS DECENT STUFF.  SO WHAT DO YOU GET FOR $33 ??

Funny you should ask!  In my search for the bottom of the “great value pile”, I looked at some items that give new meaning to the term “junk”.  But the Pyle PDA29BU.6 receiver (yes, receiver – it has an onboard FM tuner in it too!) stopped me in my tracks.  I fund this one while researching and writing (for another forum) a review of class D amplifiers for use with musical instruments in live performance.  Having schlepped 60+ pound amps around town and up multiple flights of stairs, the introduction of truly great tiny amp heads (amp chassis in separate enclosures, with no onboard speaker) and combos (the term for an amplifier chassis and a speaker in the same cabinet) has changed my life and that of every other aging guitar player.

The sound quality of today’s top shelf class D amplifiers for instruments is superb – it’s every bit as good as the best fabled tube amps of old, at a small fraction of the price, weight, maintenance requirements, and other compromises.  There are still die hard musicians (as there are audiophiles) who insist that nothing will ever be as good as a Fender Twin, Mesa Boogie, Marshall etc.  But most of us think they’re wrong.

So I’ve been going through class D guitar amplifiers to find the best values (so I can write about them) and the absolute best sounding amps (so I can buy and use a few of them).  FWIW, I now own the gold standards of class D for guitarists - a 120 watt Henriksen Blu 6 ($1000), a 40 watt D V Mark Little Jazz ($400), a 25 watt Quilter Superblock US ($299), a 45 watt Quilter Microblock ($75), and the next subject of this article – the aforementioned $33 Pyle PDA29BU.6 (which I actually bought for this article thinking it would work great as a guitar amp too).

Like all inexpensive electronics of this kind, the Pyle is a main PC board in a thin metal “project” style box.  Some of the connectors and controls are mounted directly to the board, which is generally a turn-off for me both because they feel flimsy and because they break easily since they’re usually tiny and hard to use.  But this Pyle is a cut above that.  The tone and mic / instrument input pots are actually mounted directly to the metal front panel, as are the small connectors (paired RCA line in, plus push-lock speaker out terminals).  The ¼” mic inputs are accessed through tight fitting holes in the front panel but are mounted only to the board. They do feel a bit flimsy because they’re low spring force to minimize stress on the mounting points (and they’re a lot cheaper than standard ¼” panel mount jacks).

The main volume pot is mounted on a bracket that’s secured only to the board, but it’s solidly mounted and feels a lot nicer and more solid than any other I’ve encountered in a device this inexpensive.  Assembly is clean and neat, with stain relief and support for wiring. Here’s a shot of the interior:

The output chip (which was not marked well enough for me to identify it) is on that heat sink with a layer of heat transfer material seen between it and the sink.  Everything that should be tight is tight and everything that should be freely movable is freely movable with good feel and little or no slop.  Here’s a shot of the chip on the sink:

SO HOW’S IT SOUND?

First things first, please…...everything works perfectly right out of the box.  The FM tuner ran an autoscan of our FM stations and set each one sequentially to a preset number for easy recall.  There’s only a very faint turn-on and turn-off transient that’s barely audible, and background noise is so close to zero that you really have to listen for it with your ear to the speakers to hear a sound that’s so faint it’s impossible to describe.  It’s not a hum, it’s not a buzz, and it’s not a whistle – it’s just a faint hint of white noise that’s unaffected by the controls.  And it’s inaudible to me from a foot away from the speakers.  To be as unfair to the Pyle as possible, I first set it up powering my15 Ohm Rogers LS3/5A monitors, which are as revealing and merciless a pair of speakers as any I’ve ever had.

To say that I was amazed is an understatement.  No, it doesn’t sound as good as my Prima Luna or any other good amp I’ve ever had (most of which have driven the same speakers, since I bought them new in early 1976).  But the sound is solid, rich, clean, and realistic.  It lacks the visceral excitement of great studio monitors or even my Focal towers.  The bass is solid but a bit thin compared to the Prima Luna driving the same speakers.  To be honest, I think the Pyle sounds very similar to my trusty old Alesis RA100 SS power amp, which I’ve used for years to power the Rogers in my recording setup – it’s a fine system for listening to mastered recordings.  The Rogers don’t make big deep bass, so the big power supply in the Alesis is wasted on them – and from the upper bass on up, the Pyle acquits itself amazingly well.

It’s not airy and sparkly, but it’s clean and clear.  It’s not as 3 dimensional as my Marantz 8b was, but I think it sounds a lot more “musical” than my Crown D150 (which I relegated to driving passive subs after trying it full range and finding it to be too glary for my taste).

All inputs work very well.  I hit it with BT from my iPad, line level analog from my iFi DSD Nano, and multiple musical instruments through the ¼” “mic” input jacks.  The preamp is – and sounds – simple.  From a great source (e.g. DSD through the iFi) it’s got depth and a spacious sound stage on small group and big band or orchestral works.  Strings are well delineated in Water Music and Brandenburg.  Horn sections are clean and have some separation of instruments – but there’s nowhere near the definition I get from my better amplifiers.  Even the Douk ST-01 is more realistic and life-like than the Pyle on big works with multiple instruments.

Solo piano is also decent but no cause for concern among the makers of more upscale audio amplifiers.  Brian Bromberg’s bass as heard on the album Wood is actually pretty decent – but, again, even the Douk is clearly richer and more realistic through the same speakers.  And so it goes on and on through the spectrum of instruments, styles, and source quality.  As a check performance with speakers more typically used with an amp like this, I hooked it up to my Edifier P12s, through which it did even better than it did through the Rogers or the Focals.  The Edifiers are excellent inexpensive (under$100 / pair) full range 8 Ohm passive speakers that are probably one of the best possible matches for the Pyle amp.  The amp’s output power is higher into 4 Ohms, so that’s a way to maximize available SPL – but frankly, the added power will get you only 1 or 2 dB in additional output level.  The Pyle is “rated” at 100 WPC into 4 Ohms, and I suspect it’s able to do that (at least into a purely resistive load).

You can listen to your music without a care or a concern through a $33 Pyle PDA29BU.6 and an inexpensive pair of speakers.  It’s not even close to a mid level system with more conventional components.  But the state of the art has advanced so far so fast that even this lowly $33 amplifier can make very good sound that will satisfy many, please even more, and serve most of us well as an “auxiliary system”.  It’s a handy spare to keep around just in case your “better” stuff throws a hissy fit.  It’s great for background music and is every bit as useful and enjoyable as $75 earbuds and your phone or tablet.

SUMMARY

Mo’ better stuff is flooding the market at a high (and increasing) increasing rate at low (and increasingly lower) prices.  There’s great value in the best of the latest class D amplification and the comprehensive equipment and systems built around it.  You can assemble a $300 system around a Douk ST-01, a pair of Edifier P12s, a Raspberry Pi and a NAS or even a USB drive full of music files. You can cu that to $200 by using something like the Pyle PDA29BU.6 instead of the Douk – and you can use the Pyle as a guitar amplifier too!  FWIW, I’m so happy with the Pyle as a guitar amp that I’m using it on gigs driving a pair of the amazing little Toob Metro 6.5” speakers.

Class D is alive, well, and getting better every day.  The technology sources are truly spread out around the world, and it’s a very competitive field.  The ICE modules are probably the most popular high end chips, and are found in everything from B&O speakers to Henriksen amplifiers to high end studio monitors.  TI, Qualcomm, et al are pushing the envelope hard and fast – and I think it’s now good enough to deserve serious consideration from even the most die hard traditional audiophiles.   Don’t look at the price – just close your eyes and listen!!