Amos

Hi everyone My setup is PC-> ODAC (JDS Labs)-> Digital amp When I connect the DAC to my laptop it works fine, but when I connect it to the PC, there is a kind of white-noise and the sound quality is significantly lower. The same noise continues even when I unplug the power cord from PC, so I don't think that it's a ground-loop issue. 1. Does anyone have an idea what can be the root cause of this issue? 2. Can a high-quality PCI USB card prevent suce noise? Your assistance is appreciated. Amos