Nick77,
Mike is mostly correct. The SB and DUET will play the music, but not very well. Sean Adams added some software to allow playback of 24/96 by decimating the files. That is, they drop out some information to allow the SB to play them at lower resolution (48kHz).
I would not suggest spending the extra money to buy 24/96 tracks if you are going to play them back on a SB or DUET. The "standard" 16/44.1 resolution flac files that HDTracks sells sound fantastic through the SB.
Rebecca Pidgeon's "The Raven" is a very good album. I use "Spanish Harlem" very often as a demo track.