HTPC connected to a DAC which has Asynchronous USB input. I installed the drivers on my Win7 HTPC that allows Asynchronous USB. Do I still need to worry about using WASAPI? If it matters, I'm using Foobar.
Exasound E38 Multichannel DAC
Spectron Premiere MKII 7 Channel Class D Amp (500w x 7)
2 Anthony Gallo Reference SA Amps
5 Anthony Gallo Reference 3.5 Speakers
Sunfire Super JR Subwoofer
Dell Micro PC for HTPC
Yes, you do need WASAPI or ASIO with Windows Vista, 7 or 8 for bit perfect output. This is not strictly required with XP, as some DACs, such as my Audiolab MDAC, can rebuild the original signal, as well as confirm that no bits got mangled by playing a special test track.