I think the Pass X250.5 is a great amp and I owned one for awhile. In your situation however I would try to listen to it in your system or at least with your preamp. I found that the Calypso was not a good match with the Pass/Vandersteen combination. I owned the Calypso and then sold it to buy an ARC LS26 which worked much better with the Pass. Eventually I went back to the Calypso mated to the Aesthetix Atlas amp, which works great with the Vandersteen's. I have Vandersteen Quatro's.
A better amp choice would be the Quicksilver V4 monoblocks if you are interested in tubes. I owned the V4's and Calypso combo for years and they work great together. It sounds like you are looking for SS though so I might suggest any of the Theta amps. They work great with the Calypso and the Vandersteens.If you can swing it, the Aesthetix Atlas with the Calypso is hard to beat.
Good Luck!
