Hi,
I have similar problems as it has been discussed earlier, but I have a feeling there is no solution yet.
I can make pure digital noise free recordings via USB using my laptop Lenovo T60p running Win XP, but when I use my mini PC HP 210-1023 running Win7 I get an awful hiss making the recording totally useless. I means that my PP3 should NOT be deffective but the problem is connected to Win7 and/or VinylStudio. The noise is somewhere 20-40 dB below the normal classical music levels. If I wash it out digitally it affects the music too much.
Listening to the characteristics of the noise it gets me to belive that windows7 makes the sound analogue and then digitalises it or adds some analogue noise to the digital signal from USB (Yes, I checked that nothing more than USB/NAD PP3 is selected for recording)
Even if PP3 does not have any level control I can access the recording level in Win7 (but not in XP!) and the noise is scaled with the level.
I use USB-headset so I should get pure digital path NAD PP3 >> Win7 + VS >> file >> USB-headet. But it sounds very "analogish".
My mini-PC has only a single analog sound socket (4-pin combined in/out) so the by pass AlpineSoft uses to propose by recording the analog signal is not applicable. Anyhow I purchased the NAD to get the signal digitally and not mess with poor A/D-converters inside the PC.

I hope you have a solution for this problem.
Best regards,
Corboid
(PS: I used the "set gain to 1" setting in VS level control, for win7)