which output setting sounds best?

Iam using a HP laptop running Vista 64 bit OS. Software is J Rivers Media Center 16. All music is ripped in flac. Which audio output setting gives the best sound? Presently I am using waspi. Some people tell me to use asio, others say direct sound, others say waspi. Which is the best setting for the best sound? I am running usb out to a HRT music streamerII+ dac.

Bob