Please post a picture; I think there's confusion from both sides.
Your question was answered in post #40. It's only necessary to reduce volume when ODAC is connected to multiple loads. Your external amp is a secondary load if O2 is not bypassed. The DAC is able to produce clean audio at 2VRMS when connected to a single amp. Its internal charge pump struggles under lower impedance loads (paralleled outputs), so DAC output voltage must be reduced to achieve clean output. This is easily accomplished by reducing PC volume.
And thank you again for your quick replies and also for making such an awesome little package. I love this thing!