Maybe I'm missing something, but if you go digital into your Driverack, where are you doing your Volume control? You'd have to do it digitally, before the Driverack. What are your choices of an all digital preamp?
I have done this with a Lynx Hilo (just messing around).... as it does digital routing and attenuation, and has multiple digital Ins & Outs. It's a very cool studio tool, but sadly does not have remote control. I did not notice any compromise in performing digital volume control with a 24bit signal path.