I'm very happy to report that as expected D1 helped be to get rid of all and any annoying interference I was getting from using my old internal SB...
Would USB Dac would achieve same result - maybe, But I didn't wanted to take any chances and using optical cable the sounds I hear now are only the ones I was supposed to hear like windows sound, games, music etc...
I fired up few GPU heavy 3d titles like Max Payne 3 and Skyrim and again - nothing but sound from games ...
Only minor weirdness - the volume control on D1 - it seems like it's very sensitive and very quickly moves from silent to very loud... still need to experiment more with it...
Don't ask me how it compares SQ wise vs Creative SB - I can't tell, probably because it's ether very similar or exactly same, other that getting rid of parasitic interference - I had no other expectation or goal.
Overall I'm very happy with results. No sub integration could be viewed as a CON for some, and I do hope that DAC manufacturer start to add this feature, but it wasn't needed for me.
I can not stress enough on how I absolutely can not put full size receiver anywhere near the pc so for me tiny box of D1 was a big win.
For giggles I did manage to find this AVR in local CL
Onkyo TX-SR702 Receiver / amp 7.1 surround sound - it could work, but like I said I just can't fit it anywhere close