just saw this:
http://www.gracedesign.com/news/m902%20preliminary%20info.pdfimprovements over model 901:
*has 24/192 DAC (instead of 24/96). however, I only see one AES input on the back, so I'm not exactly sure how that works
*USB connection
*Line out RCA connections in back, for easier use as system pre-amp and DAC
*has "s-Lock" feature to reduce jitter, similar to m904 and m906. I don't believe the 901 has this
* has crossfeed circuitry, to similate speakers while listening on headphones
other than that, it's very similar to the model 901. pretty interesting...