Ha ha I haven't been to this site in several months, check in today and I'm still in here. That's my Pi inside the Crack.
I don't know what mounting the DAC inside nets you if your source is still outside the amp. Still, to each their own......it is DIY.
My only comment on the whole ordeal has been that the wifi dongle that plugs into the Pi DOES cause interference but I bought a short usb adapter and stuck it slightly out the back. Problem solved. So that means my Pi and DAC are under the chassis and unshielded. ODAC is in a case and should be at least way better shielded than my rig so I imagine there is no problem there. Hook it up and lay it under there and see what happens. ODAC is inconspicuous enough I think I'd just velcro it on the back or something.