I have owned four of the above mentioned processors, and found each to have their own personalities. Please bear in mind that I used the processors purely for movies, as I have a large Cello system for music. The Cal SSP-2500 is a VERY nice sounding unit: very natural and not at all "digital" sounding. My primary reason for parting with the unit was that Cal was bought up by Sonic Blue, and the few guys left at the company didn't know anything about the product - too bad, it was a great machine (it ran very hot). The Aragon Soundstage has a wonderful reputation, but I was never impressed with it. I felt it lacked dynamics, and always sounded "mushy". The Theta Casa Nova seemed to be a fairly decent machine, but suffers from sounding a bit "over-processed" and digital, and it is definately the most difficult machine to operate thats out there. My "current" processor is the Integra Research RDC-7. This is surprisingly a very nice sounding unit. Very dynamic and natural, not at all a "digital" sound. For the money (used about $2400) it's a steal. My only fault with it is that the buttons on the front panel are impossible to read in dim lighting (they should have put LED's in the display above the buttons), and the lights around the buttons are too bright when watching movies. Having said that, when you consider all the bells & whistles you do get with the unit (including a lip-sync adjustment that very few other processors have, but should...), the RDC-7 is my current favorate. Ken G.