DAC/Pre's Digital attenuation vs. analog

Hi Robert, whether going digital or analog with attenuation it's all really about the impedance matching. Just like having to impedance match your speakers with your amps, you also have to do the same with your source and your amp, if you haven't already. Digital control can be attractive because you don't have anything else to buy, it's already remote controlled and there is nothing, no circuitry or components, being added to the signal path that can to any degree degrade audio performance. The downside is that the digital chip used in in your DAC or player should use at least 32-bit proccessing or, better yet, the newer 64-bit processing now becoming available in order to reliably avoid the sonic pitfall of beginning to lose digital resolution as attenuation is reduced below the standard (for Redbook CD) of 16 bits. So, a 32-bit player can offer 16 db of digital attenuation before reaching the 16-bit level, after which, with further reduction, you begin losing digital resolution. That, at some point, begins to darken the sound and small musical details increasingly begin to fall away from the presentation. This effect becomes harder to perceive as the overall volume level drops however and some have even claimed to have not heard a significant adverse impact on the sound as a result (although, I don't find myself among them). But, 16 db should be enough attenuation for most people and purposes and the 48 db offered by 64-bit chips would be enough for anyone. Analog controls have their own advantages and disadvantages. A big advantage is that you are freed from the restriction of having to pay for high processing power in your source. That fact may also give you a little more leeway when it comes to impedance matching your source and amp before you buy. For an example, I have in mind a product like Scott Endler's Stepped Shunt Attenuators (which, as his site will inform you for performance reasons, you can ONLY use by installing them physically at the inputs of your amp(s), without any cabling between them and the amp). These things use surface mount resistors which I can tell you are very transparent indeed (I've been using a pair for years) and there are only 2 resistors in the signal path per channel at a time - one for the ground and one for the value of attenuation that's being selected. There's even a possible way of adding remote control to the 24-step versions available in a DIY kit from Bent Audio, though it's not particularly cheap, itself. The Endler attenuators are about $200 a pair, still about 1/10th the price of a good and sonically equivalent active preamp. In my rig (a relatively well impedance-matched system from source to speakers) I heard little difference in sound quality going back and forth from the Endlers at -4db attenuation (full output) to removing them and listening to the DAC fed into the amp with no attenuation whatsoever (on the same quietly recorded CD's). Only a faint reduction in the silkiness of the highs was the only difference that test has revealed to me, but, again, and I can't stress this enough - impedance matching when going preampless is everything, so take your time with that part and it will reward you well with the rest of it, either way.

Doh!!, just reread your OP and realised you're looking for specific advice, not general, sorry. My vote (of the 3 you mention) might be for the DAC2, provided you feel 16 db of attenuation is ok for you. This would inherently be a bit better (or at leat more direct in terms of transparency) than either the DAC One or the Bryston. However a quality active preamp usually works to 'improve' for lack of a better word the soundstaging of a well suited amp. An amp fed directly may offer a more live sound and an amp with an active pre in the price range of the Bry may have a wider or deeper stage (or both), but the degree to which that's true may vary depending on both the quality of that preamp (again, shouldn't be a real issue for the Bry) and how well it was impedance matched to its amp - like I say it all tends to come back to matching, but amps driven straight can (though not always) have slightly smaller stages (though no less coherent or 3D). If there's any way you can audition your amp temporarily, before you decide on anything, being fed directly from a CD source with 32-bit attenuation, then you can compare to your current pre if your using one, both in and out of the signal path, and get at least some impression of the general differences involved. The Bryston may end up being somewhat different in this regard than with your current pre, but this audition should show you the basics. I have actually valued transparancy more than soundstage in this circumstance with my own gear, but of course it may be the other way around for you.

I have done a few shootouts between setups using volume controls on the DAC, and uning preamps, and finally ended up settling for "DAC direct" (PS audio perfectwave MKII). Prior to the arrival of the MKII, I found a slight advantage in using an very expensive (tube) preamp. Based on my experience, I am quite confident concluding that for a given budget, and with no need for input switching, DAC direct will give you the best results - considering you can buy a better DAC with the money you save on the preamp. If you don't have the time/appetite to circulate different pieces of gear through your system and make the decision based on your own observations, I would have no problem recommending going the DAC2 route. You will also save cabling funds, which can all be applied towards better hardware elsewhere in the chain.

Hi guys. I should have mentioned that my main concern is at low volumes. I was thinking that maybe digital attenuation would be to my dis-advantage. I'll be playing .flac files through foobar2000 exclusively (which has a digital volume control itself). Would it be best to leave the foobar volume control all the way up?

I'm having a hard time agreeing with "32bit offers only 16dB of attenuation before eating into the 16bit resolution of Redbook".
As far as I know, every bit accounts for 6dB, thus 16x6 would mean that a DAC chip working internally on 32 bit will offer 96dB of digital attenuation of a redbook stream before loss of information occurs. And that's pretty much the entire dynamic range of redbook.
Attenuation in the digital domain is no longer the bad thing it used to be, with the advent of these 24-32 bit DAC chips. The myth, though, will continue, I'm sure.