how to make a remote-controlled 8ch attenuator?

don't use Creative cards..

if you go for an M-audio delta,or something similar you can bypass the windows volume control and control the DAC's on the card itself.

I'm using a M-audio revolution 7.1. this card uses the windows mixer for master volume, but i wrote a small tray application that controls the 8 DAC's simultaniously, and in that way bypassing the windows mixer. the master volume is always max.

i also looked into creating a computer controlled volume control using digipots, but this is way out of my league, so I abandoned this project..