Differences in sound: DAC vs. DAC + Pre-amplifier

[Kimo]

8 minutes ago, photonman said:

I have had my Benchmark DAC3 for almost two weeks now and could not be happier.  It is great to have hardware volume control just for the convenience and control.  The Benchmark is a no nonsense black box made out of bent sheetmetal and all in all it sounds very good to me.  My setup is very simple:  Mac to DAC to Amp.  The OP's question is really hard to quantify with results and it all is a balance and wants and needs.  I am sure I could get better sound but for my wants, the sound has not suffered with this remedial DAC/Pre combo.  I am also very happy that I now have balanced analog out to my class d amp.  The volume control for digital into this DAC is in the digital domain.  Vice versa if you use it as a preamp, analog in would have volume control in analog domain.

 

I have talked with Benchmark and they indicated that the best measured performance was obtained by using the DAC at a fixed volume and employing their preamp.  They also said the improvements were only really noticeable on things like reverb trails and only on certain recordings, so you are really digging deep at that point.  

 

Generally speaking, your SNR will suffer with the insertion of a preamp, but you may still prefer it for other reasons.   

[Kimo]

1 hour ago, barrows said:

The above is false.  the statement: "nor a system impediment" is what I am referring to.

 

A preamp in the signal path does this:

 

Losses of fidelity from:

 

Preamp input switching devices

Preamp gain stage

Preamp analog volume control

an additional interconnect

At least two additional connections per channel (XLR or RCA jacks and plugs, plus their soldier joints to wires)

 

All of the above mentioned items are lossy, noise and distortion sources which can only add noise and distortion and reduce fidelity.  Remember, that distortions and noise are additive throughout the system.  Removing the preamp (and this applies to any preamp, no matter how good) removes these sources of noise and distortion.

 

Benchmark will tell you that you will get better performance using their DAC 3 at a fixed setting and inserting their preamp.

 

ESS will tell you analog volume controls are better than digital.  I think there is a paper online from them with measurements.

 

That being said, I don't run a preamp in my system, and doubt that I would go back to one.  I guess I would, if I switched to an all Benchmark System.  I might consider one if I went back to a tube amp.

[Kimo]

36 minutes ago, barrows said:

 

I would expect a manufacturer who manufactures and sells a preamp to say this.

 

 

You can find Martin Mallinson's video from RMAF on Youtube.  Be careful how you interpret it though. if you pay attention, what he is saying is that analog volume control has an advantage IF you need to use tons of attenuation.  A digital volume control is demonstrably more transparent than an analog one as long as it is not used at very high levels of attenuation.  For example, the ESS chip's volume control runs at 32 bits, so, with a 24 bit source file you have 8 bits extra for volume before you lose ANY resolution.  8 bits means that you can have attenuation up to (8*6dB) -48 dB.  The other potential drawback with digital volume control is thta it does not reduce the noise floor as the volume is lowered, again, this is a non-issue unless you use very high amounts of attenuation, and have a noisy source, both are non-issues in the vast majorities of real world systems.

 

Call Benchmark and they will describe to you in detail why they achieve better performance with a preamp.  I don't think that they will pitch their preamp.  They didn't when I spoke to them, but time is gettin harder.

 

Here is the link to the ESS paper.  It is an old one.  Maybe not as relevant these days.

 

http://www.esstech.com/files/3014/4095/4308/digital-vs-analog-volume-control.pdf

 

I have always found them to pretty much suck, but maybe I just did not hear a decent one.

 

 

 

[Kimo]

1 hour ago, Miska said:

 

Problem is that for example ESS has inherent series resistance of 600 ohm which defines the thermal noise limits. With analog volume control you are going to have hard time finding one that has equal or less inherent resistance. In addition you'll need additional analog buffer/impedance converter sections which also will have some noise and distortion.

 

 

 

 

My DAC employs a log ladder network to create a constant impedance passive attenuator, for whatever that is worth.  I can't tell the difference between fixed mode or the attentuator.   I tried but failed.

 

My amp has a pretty high SNR, so apparently it is possible to make an analog volume transparent to me at least with an ESS chip.

[Kimo]

10 minutes ago, Blake said:

@barrows can correct me if I am wrong, but I don't think he has issues believing there are people who subjectively prefer the sound with a preamp inserted, he is just speaking from a technical perspective, DAC direct to power amp will be technical "more transparent" which is correct.

 

 

 

Not according to the guys who make the most transparent electronics in the world, as I pointed out earlier.  

 

 

[Kimo]

3 minutes ago, Blake said:

 

I might have missed that.  Which company makes the most transparent products in the world (sorry if your comment was tongue in cheek)? 

 

 

Based on SNR, Benchmark.

 

Although, I believe there was an Apogee DAC that measured even better than what they can do.  I suppose if that were true, you would need to substitute the Apogee for the DAC 3 in the Benchmark system.

 

Of course, they may make the only preamp in the world that qualifies, but at least there is one, apparently.

[Kimo]

4 hours ago, Miska said:

 

You can get some additional transparency by omitting that ladder network and extra buffer stages and going with a good digital volume control instead.

 

 

I am pretty sure Mr. Linnenberg would not agree.  Dynamic range is specified as 138 db.  Anyway, I use the line level inputs for the vinyl rig, so I need an analog control somewhere.

[Kimo]

9 hours ago, barrows said:

 

I am curious as to what this refers to?  DR of what exactly, as this number is at the extreme end of what is possible in the analog realm (and only for line level, amplifiers, not at all...)

 

Yeah, who really knows.  We would be talking 23 bits.  I am not even sure that parts exists that could hit that number.  Are there resistors available that are that quiet?

[Kimo]

2 hours ago, Miska said:

 

I don't know who is Mr. Linnenberg, I can let him disagree, no problem.

 

Even at 32-bit PCM output, without noise shaping, dynamic range is 192 dB. And with noise shaping you can push it to for example 240 dB or more. And then if the digital volume control errors are at or below -300 dB, I would say that is quite a bit better than you can do in analog domain.

 

 

But once it hits the analog realm, does any of this matter?  If you built a room quiet enough to hear or not hear any of this, could you actually sit in it very long?

[Kimo]

11 hours ago, sandyk said:

 

 Actually, many Power Amplifiers these days have an Input Impedance of 10K to 20K which usually results in improved S/N as well as contributing to a lower DC offset.  e.g. Audio Power Amplifier Design Handbook 5th ed - D. Self.

 

My DAC has a fully balanced output of 300 ohm per phase and my amp has a fully balanced input of 94K.  

 

Do you see any problem with these numbers?

[Kimo]

16 hours ago, barrows said:

I do not think so.  We can use the process of elimination here.  The truth is that there is no actual technical problem with how the Bricasti DAC drives the input stage of the amplifier, that is a fact which is not challengeable.  Then, given that fact, what are the possibilities for how the "additional body" is produced by the addition of a preamp?  Can anyone reading this suggest a means by which the addition of the preamp, in this example, produces produces "additional body" other than by adding something of its own to the playback?  If the preamp is adding something, that addition can only be a coloration, as what other possible option is there?  A preamp cannot magically know how a recording is supposed to sound, and then add in the needed additional aspects, all it can do is add in a color of its own through its imperfections. 

 

Audio playback systems are not magical devices operating by properties which we do not understand, anyone who takes a position suggesting that they are might re-consider that position.

 

As to sound differences, I have described my own experience in specific sound differences in a previous post in this thread where I discussed my process moving from using a preamp in my system, to eliminating it.

 

So, the only preamps that aren't screwing up the signal are thin sounding ones?

[Kimo]

16 minutes ago, barrows said:

 

Ummm!  I do not know what to do with this, either you are joking, you did not actually read my posts, or your reading comprehension is compromised.  I hope it is the first option!

 

But, to ease your mind and clarify on your post:

 

If one is looking for a system which is transparent to the source recording, the system should not editorialize on the recording.  The system needs to be transparent to the recording.  The goal of any preamp for a transparent system should be the proverbial straight wire with gain (and source switching, and volume control).  It should neither be "thin" sounding nor be "rich" sounding, it should add no sound of its own whatsoever.  In practice, this is never the case, but that should be the goal (from a technical standpoint, in some systems, there are likely preamps which in practice add no audible sound of their own).  If a preamp ADDS a sound of its own, that is by definition a coloration, as the preamp has no "knowledge" of what the recording should sound like, and therefore cannot "improve" it.

 

And again: if one prefers the sound of their system with a colored preamp in the system, I am fine with that, as long as one accepts that it is a coloration, and not revealing of the actual recording.  

 

Well, if this is the goal, shouldn't you start with a truly neutral speaker?  

 

Briefly, I owned a pair of Dynaudio Craafts.  The legendary king of neutral speakers, though I did not own the active pair.  Sit six feet away, turn up the volume and still be sort of bored.  That Esotar tweeter could do some dynamics though.

.

I am not so sure that the output stages found in most DACs are always more neutral than most preamps.  Maybe so.

 

The loss of transparency suffered by adding a preamp could be very real.  Outside of Benchmark, it would seem that you are going to need to spend decent cash in most cases to maintain your 20 bits.  

 

 

 

 

 

[Kimo]

Just now, barrows said:

If you have not read my previous posts, I have made the distinction of my preference for a system which is hi fidelity, which means transparent to the recording.  All of my other thoughts here are referenced toy that point of view.  Additionally, I have made no judgements about those who might have different preferences.  If you like SET amps, that is fine with me, if you like adding a preamp, that is also fine with me, your audio system is for your enjoyment (and hopefully that of your friends and family).  If one prefers a colored sound, rather than an accurate one, that is fine with me.   

 

I doubt that my system qualifies as neutral with all Linnenberg Electronics and Alta FRM speakers, but unless you are running active monitors with DSP  you aren't running a very neutral system, preamp or not.  JBL with Crown will get you closer to neutral.

[Kimo]

14 minutes ago, bodiebill said:

Some of us believe that digital is in principle flawed and that, even at higher resolutions, some essential information is missing from the signal. Compare it to film cameras of the first decades of the 20th century.

Is it unthinkable that some coloration can correct these flaws and heighten our sense of 'being there'?

See this enhanced/distorted/smoothened/colored clip of New York in 1911:

 

 

 

Here is link to a Bob Katz  article about improving sound via the addition of distortion.  Bob is pretty well known in the professional sound world.  

 

https://www.innerfidelity.com/content/katzs-corner-episode-25-adventures-distortion

 

In a nutshell:

 

No distortion sounds better than a little bit of bad distortion, but moderate, well-distributed distortion sounds better, too!. I believe there's a middle amount where distortion can sound deadly. Why? Because in that middle area, where the overall distortion measures somewhat low, but not close enough to zero, the presence of some higher harmonics can psychoacoustically predominate over the important lower ones. In other words, the distribution of the distortion is the key to sonic differences.

[Kimo]

3 minutes ago, barrows said:

As to the Bob Katz approach:  We are living in a time where current technology allows us to have no audible distortion in playback electronics at all.  While the approach of accepting some low level distortion in electronic design was once the best compromise we could make, now we can have none, which is even better technically (leaving loudspeakers out of the discussion).

 

As an example of what I ma talking about, I would encourage anyone to listen to a Mola Mola DAC and Kaluga amps driving some really really good loudspeakers, such as Vivd Audio.  When I heard this combination (I think about 4 years ago) it was a landmark experience for me because the level of detail was very fine indeed, as was the realistic portrayal of dynamics, and timbre.  But what was really astonishing was that all of these sonic qualities were achieved along with a sense of naturalness, organic sound, and ease which did not sound like an electronic representation of music at all, but just like music itself.

 

Bob does call out the Ncore amps as being "audibly close to straight wire with gain" specifically in the article, but he really doesn't say too much more about them.   I can't tell if he would prefer to add a little 2nd order distortion to the Hypex, or not, from what he has written.

 

Still, the implication is that most amplifiers, as of the articles date 2018, will sound better by adding a little second order distortion to mask IMD and higher order distortions.   Personally, I never enjoyed a tube preamp with a solid state amp, but lots of people do.  If we go with Bob's approach, it would stand to reason that removing the preamp might make many systems sound worse.  

 

[Kimo]

On 3/30/2020 at 11:56 AM, barrows said:

 

IME, these days, there is no benefit anymore for the best class A amps vs. the best class A/B amps, as the crossover distortion problems have been solved by good engineering.  Given the insane waste of energy of class A, I consider them bad engineering at this point, as they offer no benefit anymore, at least not that I can hear. 

 

 

 

 

 

Could you please elaborate on the modern new exotic engineering revolution that has magically made crossover distortion disappear?  I think some of those bad engineers like Nelson Pass would be interested in learning how to improve their designs.

 

 

[Kimo]

2 hours ago, barrows said:

This is not news, or anything new.  Class A/B amplifiers have been equalling or outperforming class A for a long time now.  

 

I suppose you do realize that Pass Labs makes both Class A and Class A/B amplifiers, right?

 

Please do not put words in my mouth, I did not call anyone a bad engineer, and certainly not Nelson Pass who I have an enormous amount of respect for.  

 

I find statements such as the above inflammatory (and maybe emotional?) and not conducive to good discussions in any way, perhaps you might like to re-think your approach.

 

As to excellent class A/B designs with low levels of distortion, I suggest you might have a listen to a Bricasti M-25 or anything from Constellation, perhsps...

 

I used to own a Pass Labs, class A/B amplifier, but after quite a few direct comparisons, over the course of a year, i ended up preferring my DIY Ncore based amplifier, this experience was turning point for me.

 

Nelson and I are still waiting for an answer to the question.  The guys from Benchmark might be curious to learn how this all works as well.  Seems like they spent a lot of effort trying to eliminate crossover distortion.

 

I imagine there are posters here that can answer for you, but you keep pushing them away.  Maybe, you should shut up for awhile and let those guys talk, so we could all learn something here.