Digital volume control question...

Hi all,

A little background first. I am planning on getting a Wyred4Sound DAC2 and feeding it directly to my amp, which powers my Magnepan 3.6s. (I also plan on getting the W4S ST/SX 500/1000.) And I listen to 70% 24-96, 25% Redbook and 5% 24-192.

Now I know that the W4S volume control is well-implemented and 32 bit. So I’m not too concerned, although I know that there will be SOME signal loss. My question has to do with which amp I should get, given my normal listening levels, (apartment friendly), and about the levels at which the DAC2 begins to degrade or decimate the bit depth through those different amps and into those inefficient Maggies.

I assume that at my normal sound levels and with the more powerful amp, that the DAC2 would begin to degrade the bit-depth SOONER (or at a lower setting), than it would with the less powerful amp producing the same db level. Am I correct here, or not?

(This question will be posed to W4S too, but I wanted an unbiased opinion, also.)


Hello Micheal, based on my own limited experiences you will need an amplifier with an input impedence that is compatable with your Dac of choice but of suitable drive for your Maggies.

Better if the amplifier is equiped with good attenuators so to pad down the the signal at the same time as with the digital attenuator on your Dac.

Both analog and digital volume controls sound best in their higher positions.

I believe the Weiss Dac 202 has a four step analog control via stepped resistors and a good dithering digital volume control and low output impedence output stage to drive the amplifier of choice directly without issue, there may be others .

My present setup is a Server via Firewire to a Weiss Int202 which has a dithering digital volume control then Aes Ebu to a an Audio Research Dac8 driving a Vac Phi300.1 which has analog attenuators to my speakers.

This works a treat for me, John Bent of Bent Audio klndly pointed me in this direction some time ago.

I hope this may help , thank you.
It has to do with the gain of the amp. Higher gain will allow you to use less of digital volume. The lower this drops, the better. 0 is best of course, but you will need really high gain to get this. The rule of thumb that I use is no more than -10dB or it will impact SQ. If you are using ONLY digital volume, it will likely require at least -20dB.

BTW, the DAC2 sounds best when driven with I2S, either from the PWT or the Off-Ramp 5 HDMI from a computer.

Steve N.
Empirical Audio
Mkh1099 --

Given your fairly inefficient Magnepan 3.6's and the potential use of a digital volume control operating within a full, true 32-bit domain I'd perhaps downplay the importance of poweramp gain compared to the attention needed matching the poweramp and DAC in a direct connection. It's not that gain is entirely unimportant (i.e.: seeking the lowest possible value here, albeit an unnecessarily restrictive measure), but in your case - with the 3.6's being a non-variable and a 32-bit digital volume control a likely implementation - I'd concentrate on finding the poweramp-DAC combination that sounds best to your ears (impedance output/input matching has been mentioned above), gain disregarded; pragmatically speaking I believe much of the emphasis placed on "signal loss" with a digital volume control - certainly in the 32-bit domain and with speakers as (relatively) inefficient as yours - is out of proportion, and predominantly a theoretical/academic discussion. That said, being that you play back mostly 24/96 material I'd recommend you stay in the 32-bit domain volume attenuation..
Thanks for your answers so far - they are all helpful!

More comments... ?

Probably will be a good idea choosing an amp that has a low input sensitivity. Given the DAC will output around 2V, you don't need an amp with 0.5V sensitivity, for example.

Furthermore, given you should avoid anything lower than -18dB (max) digital attenuation, maybe a good idea is to build a simple two-resistor attenuator at the power amp input (can be also done inside the interconnect cable), so you can fit in around 0-12db range from the DAC digital attenuator for your normal listing levels. That will give you best sound, IMO.

Alex Peychev