Windows XP and ASIO works just fine. If you are just sending PCM out a USB port there's no reason for anything as long as you configure your "player" correctly. Foobar can be configured not to change the bitstream, same for J. River Media player.
I'm assuming your using .WAV files or lossless compressed files, eg. FLAC. There's not much to reading a file, decompressing if necessary, and sending it out a USB port.
I'm assuming your using .WAV files or lossless compressed files, eg. FLAC. There's not much to reading a file, decompressing if necessary, and sending it out a USB port.