Anyone else connect their DAC straight to their amp?

[ggking7]

I currently connect my Wavelength Proton DAC directly to my power amp. The Proton allows the volume to be controlled by the computer and all of my sources are on the computer (FLAC, CD, DVD, Blu-Ray, TV, etc) so I can skip the preamp and extra sets of interconnects.

 

I was getting excited about the HRT Music Streamers, but I was just told by HRT that none of their DACs have any sort of volume control. Is anyone else connecting their DAC straight to their power amp? The DAC volume control is essential in order to make that direct connection. Software mixers are obviously not an option.

 

[bralk]

Yes - Benchmark DAC1 HDR with analog volume control into ATC SCM 100 ASL active speakers. Works OK.

 

cheers

 

[Audio_ELF]

One of the issues where you use a direct connection from DAC to Poweramp (where the DAC doesn't include analogue volume) is that where you have to reduce the volume a long way, the noise relatively increases as the digital volume is lowered (in software).

 

Your only other option is a basic passive volume control such as TC Electronic's Level Pilot - use this for the major changes in volume and then software via remote for everyday changes.

 

Eloise

 

PS. I don't think any of the HRT Music Streamer DACs would improve over the Wavelength Proton...

 

[Al Jones]

I tried running my Wyred for Sound DAC2 straight into my active MK 150 monitors/MX350 subs, but the sound seemed to "dry up" and catch a bad case of digititis compared to having my Gryphon Audio Designs Sonata Allegro preamp in-line and running DAC2 at full output.

 

Had the same experience with my previous DAC/music server, Logitech Transporter.

 

Whittling away at precious bits with a digital volume control definitely doesn't work for me.

 

[Ajax]

In my experience the best results always happen when things are kept simple - the KISS principal.

 

As per a previous contributor to this thread, I also use the Benchmark DAC1 HDR with analog volume control direct into active speakers, in my case ADAM A7 studio monitors. The system works better than OK, the sound is stunning.

 

For critical listening I prefer J.Rivers with WASAPI on a Vista O/S with files recorded in the AIFF format. For whatever reason it is a much more involving sound compared to iTunes on my Macpro when also played through the Benchmark and ADAM A7 speakers.

 

There are a lot of superlatives currently in vogue to describe how something sounds, which in my opinion have little meaning because everything is so subjective, but all I can say is that after 2 years of experimenting with J.Rivers on a PC and iTunes on a Mac Pro I much prefer the sound of the J.Rivers/PC.

 

I wish I didn't because I "grew up" on iTunes and know it backwards and greatly prefer it as a file management system, however, I really enjoy the sound from the J.Rivers/PC set up.

 

Currently I download high res 24/48 files from Society of Sound ($50 for about a dozen albums) and play them through a US$1,500 DAC and $1,000 active speakers and have a sound that really excites me and is so much better than my old analogue system being a 1982 Linn Sondek with ittok arm turntable and naim nait amp and linn kann speakers.

 

I never took to CDs and have been out of the Hifi loop for many years but high res music combined with a well configured computer / DAC and active speakers has given my love of music a new life.

 

 

 

 

 

[Audio_ELF]

As per a previous contributor to this thread, I also use the Benchmark DAC1 HDR with analog volume control direct into active speakers, in my case ADAM A7 studio monitors. The system works better than OK, the sound is stunning.

 

Yes and no...

 

Using a Benchmark DAC1 HDR into ADAM studio monitors works well, but you are not doing what the OP asked about; which is not using a pre-amp. In fact you actually have 2 pre-amps / analogue volume controls - one in the Benchmark DAC1 HDR and 1 in the ADAM A7 monitors.

 

I stand by my original comment that... using a DAC, which is not designed to be, connected directly to a power-amp is unlikely to give good results... That doesn't mean that some DACs aren't designed to be used direct to a power-amp.

 

Eloise

 

PS. Appologies to Florence Welch...

 

[The Computer Audiophile]

Hi Eloise - Love the Florence & The Machine reference :~)

 

[ggking7]

The Proton's computer-controlled volume control is done in the analog realm. That may be why it's working so well for me too. In that way, there is a sort of preamp stage built in, but skipping an external preamp and extra set of interconnects conforms to the KISS principle and sounds great.

 

Regaring the HRT vs. Proton, it's true that the Proton should outclass it (I've never heard an HRT) but the Proton lacks galvanic isolation. To solve that problem, I'm using a DIY Paradise Ultravox powered by an SLA battery. Additionally, powering the Proton via SLA battery instead of relying on DC/DC conversion to eliminate noise from USB power (as the HRT does) should (in theory) provide much cleaner power.

 

[nyc_paramedic]

Yes, the Proton responds to the volume control set by the computer, but it indeed sets an analog volume circuit incline with the DAC instead of the digital domain. I don't know the specifics of the volume circuit (passive, active?), so you'll have to shoot and email off to Wavelength Audio if you want to find out.

 

I connect my Ayre QB-9 to amp via a Placette Remote Volume Control; a passive design with nothing but mil-spec relays and Vishay S102 resistors in the signal path.

 

Some people use the term pre-amp to mean anything that controls volume, when in reality a "pre-amplifier" should signify an active circuit of some kind. Though, exceptions should be made for passive volume controls that only have buffer circuits (e.g., [1]Placette Active Line Stage and the [2]Nelson Pass First Watt B1 Buffer "Preamp") for impedance matching.

 

 

[1] http://www.stereophile.com/solidpreamps/1107pla/

[2] http://www.firstwatt.com/b1.html

 

 

 

[kana813]

I'm using a PWD to drive the balanced inputs on the Bryston amp modules in my PMC AML 1s and it works and sounds great.

 

 

[Ajax]

Hi Eloise,

 

I stand corrected - of course the Benchmark is a combined preamp/DAC, it is even advertised as such.

 

I was more trying to illustrate that you can get excellent sound from a very simple system, however, as you point out that's not what this thread is about so I will butt out.

 

[Mr.C]

I was trying an apogee dac direct to bryston power amp and it sounded very nice, even using digital volume control *gasp In fact, I thought it sounded less forced than using a preamp in between, so don't be afraid to try digital volume if you trust your ears. My speakers are also inefficient enough that full volume is loud but not deadly.

 

[Miska]

I was trying an apogee dac direct to bryston power amp and it sounded very nice, even using digital volume control

 

Well implemented digital volume control can be very good. And no bits are necessarily lost.

 

It is misconception to think that analog volume controls wouldn't increase noise - they do. How it behaves vs. volume setting depends on implementation details.

 

So the whole volume control question is not black and white...

 

[Audio_ELF]

Miska ... first off I'm not saying the digital volume controls are not good; however is it not correct that in an analogue volume control, both signal and noise are reduced where as in a digital system the signal is reduced while (analogue) noise stays the same so the SNR is vastly reduced. This can cause problems where large amounts of volume reduction is needed (depending on the rest of the system).

 

Eloise

 

PS. Mr.C - what Apogee DAC are you using?

 

[Miska]

however is it not correct that in an analogue volume control, both signal and noise are reduced where as in a digital system the signal is reduced while (analogue) noise stays the same so the SNR is vastly reduced

 

All resistors have value dependent thermal noise. At best, the noise floor remains the same, thus equalling a digital volume control. With a potentiometer, series resistance increases and parallel resistance decreases as volume is lowered...

 

On digital side, yes, noise floor remains static so the SNR is lowered as function of volume.

 

Distortion behavior is more complex and depends a lot on implementation details. In both domains...

 

[blueixus]

As Miska says Digital VCs should not be considered lesser than their analogue equivalent, it may be the fact that the very opposite is true.

 

Before I moved to the world of Computer Audiophilia I spent time and money exploring Analogue Volume Controls; Placettes, DACTS, Goldpoints, Bents, Dantimaxs all came and went.

 

For my money none can match a well implemented digital Volume control, I really like the volume control in XXHE. Really well thought through.

 

So for my money DAC direct to Power Amp is best, with the following important caveats:

 

1) The Dac needs to have the right drive and to be properly matched to the Power Amp on I/O impedance - not that easy - I needed to have a small mod made to my Audio Note DAC

2) Extreme care and diligence needs to be taken not to accidentally release full volume into the speakers.

 

Eloise is right to mention low volume listening, for me the gain in overall performance outweighs this and I don't often listen 'critically' at low volumes.

 

It has worked really well for me, the only value I can see for a PreAmp now is for source switching.

 

Obviously if one has Analogue sources the traditionally preamp retains a purpose, a proper VC bypass for inputs using digital volume controls would solve this solution.

 

 

 

[stejorge]

And the Gallo Ref 3.1 has never sounded better.

I used to run a Lyngdorf 2200 on them earlier, but this settup is better by a big margin. It's sweeter sounding and dead quiet.

Reading the 6moons review this was also the prefered way to run this DAC

But this would of course be dependent on the equipment you are running. And you need to match the gain on the amp/dac

I can't hear any degradation in sq on normal listening levels, only when turned down to a very low level there is an audible sound degradation ( as if listening to mp3 files instead of flac)

 

[Audio_ELF]

Everyone who is responding ... "I use a Benchmark DAC" or "I use a W4S DAC-2", etc, etc. is missing the point - all these DACs are designed to be used direct to a pre-amp. DACs such as the HRT are NOT!

 

Eloise

 

[Ajax]

Hi Eloise,

 

your quote "I use a Benchmark DAC" or "I use a W4S DAC-2", etc, etc. is missing the point - all these DACs are designed to be used direct to a pre-amp ..

 

 

Don't you mean direct to a "poweramp" as the benchmark is a preamp / DAC combination. I am not trying to be a smart arse I just want to make sure I understand.

 

[Audio_ELF]

Yes: Benchmark DAC1, W4S DAC2, Wavelength Proton are all designed to be connected direct to a poweramp.

 

Eloise

 

[stejorge]

their as in "HRT's dac"?

If he refers to HRT why even ask, as he knows already it does not have any volume control and software control was not an option?

 

[Miska]

Benchmark DAC1, W4S DAC2, Wavelength Proton are all designed to be connected direct to a poweramp.

 

Not that it should matter. Poweramp should have same input impedance as preamp. For line level sources, "gain" of 1 is usually way enough for "pre-"amp. Mostly these act as active attenuators, except for LP...

 

Some poweramps or active speakers have built-in sensitivity/volume control, making even purely software based volume suitable.

 

Edit: thus the maximum possible volume is limited by the hardware setting not touched later on and the actual adjustment done in digital domain...

 

[barrows]

First, re noise. If one suses the digital volume control built into the DAC chip (or in software) here is what happens:

1. Bit reduction will reduce resolution, 1 bit is lost for every 6 dB of attenuation-if one does the math one can see that for 24 and 32 bit DACs, only when very significant attenuation is applied is there any loss of resolution, as no DAC achievs better than 19 bit rue resolution in its output. Additionally, at high levels of attenuation (low volumes) one woudl not be able to hear the "lost" bits anyway. So, resolution loss is really a non-issue. Quantisation noise might be another problem in some cases though-I am not qualified to address this.

2. Noise. A DAC chip has a noise floor, its own self noise, usually at -120 to -140 dB. When you attenuate the signal with the digital volume control on the signal is attenuated, the noise stays at the same level. So the S/N ration drops as the volume is attenuated. When the signal is attenuated by an analog volume control both the signal, and the noise are attenuated equally, so the S/N ratio is preserved at all volumes. From this we can conclude, again, that only at high levels of attenuation will this present any audible problems.

Disregarding Quantisation noise and dither (maybe one of our digital design experts can comment on this) We can conclude that as long as your system does not require high levels of attenuation (beyond -20 dB) for reference level listening, a digital volume control should be OK. Furthermore, even for high levels of attenuation the digital control is probably OK because low level details are obscured at low levels anyway, as they drop below the noise floor of the system.

DAC direct: there is another issue, is the output stage of the DAC capable of driving the input stage of the amplifier for best performance. This is all over the map, some DACs have quite capable output stages, others do not and will benefit from a preamp. Length of interconnect to the amp will be a factor as well, as will the design of the interconnect. There are so many variable here that one really has to try this in their system to know for sure.

And, yes, an analog volume control will add both noise and distortion to the signal, including passives, and buffered passives. So digital volume control may be preferable sonically in many systems. As usual, it is implementation and the details that matter, with no easy answer. I recommend trying yourself and deciding these issues by listening in your own system context.

 

[ggking7]

Please correct me if I'm wrong but I think the Proton is the only DAC with the following features:

 

Linux compatibility

asynchronous mode

volume control

 

[Codifus]

.....or in a very small club where the DAC has a software controlled analog volume control. Most DACs fall into the 2 categories where they either have an analog volume control or digital volume control.

 

CD