Gaming is not the main use of the HTPC. Once in a while I do play a little bit, but nothing that would make me loose sleep over the gaming sound.
I use the HTPC 50%/50% between movies+tv shows / music. The main concern for sound quality would be in the stereo áudio, for music listening.
When I have the Money available, I’ll try to get a proper external DAC. Maybe a used Audiolab MDAC, when they start appearing on the 2nd hand market.
For now, I guess I’ll stick to the old sound blaster live! 24bit, since it is external, and according to some people it make's a difference if the soundboard is better isolated from the HTPC’s internal electric noise. Wouldn't have that with the X-Fi.
Anyway, thank you all for your opinions.
PS: I’m running Musicbee with Wasapi.