Hi azzd,
I THINK, that using any volume control before DSP processing is not a good solution. The best would be to use digital source (such as CD digital out, or computer card digital out) and connect it directly to the DSP processor. DSP would do all desired signal processing and attached DACs would convert the data in to the desired number of analog channels. I THINK that AFTER DACs conversions volume control have to be done, the best, on the power amplifiers inputs. I am aware that it would not be too practical to manage , say 8, analog pots. Some amount of output dynamic can be managed digitally , especially if larger number of bits DACs are used ( 24 or 32 bits per sample).
The problems with the signal wide noise or his can be annoying if high efficiency drivers are used connected to the power amps with large amplifications, usually of high-power type.
Interesting to read:
http://www.androidauthority.com/why-...it-dac-667621/
regards
ivica