I HAVE HEARD THE X-DAC AND THE MODEL PREVIOUS TO THE TRIVISTA 21. I DID NOT LIKE EITHER OF THEM I CERTAINLY WOULDNT PAY $900 FOR THE X-DAC. LOOKING FOR A DAC TRY THE BENCHMARK IT SMOKES THE X-DAC.
Haven't heard the X-DAC but have the Tri-Vista. Terrific DAC. All the comments about soundstage, air, detail are true. Can play heavy classical without getting congested. With this DAC you are not just listening to music, you are listening to musical instruments. Not tolerant of poor quality transports though so if you are thinking of using it with your cheapo dvd player, you won't be happy.