I also recommend the XA100.5. In my review on Audiogon, I compare it to other Pass Class A amps that I have owned, and it is by far the best of the bunch and it can handle difficult loads. You will also have the advantage of mono blocks over the stereo X350.5. I have not heard the X350.5. Mark @ RENO might even have a good demo listed. I bought mine from him and it was in excellent condition and I saved some money. Two audio friends heard my XA100.5 driving my Egglestons and both called RENO and ordered pairs.
Pass Labs amp choice for CLS - What would you do?
After much reading and soul searching I have decided to upgrade the amp on my CLS speakers. I can buy a used X350.5 (current generation) or a pair of X600 mono blocks (previous generation - can't afford the X600.5) for a similar price. Is the .5 model change significant? There is no way that I can audition/compare them on my system, so I will have to take a leap of faith. I know I can't go wrong, but what would you do? And what pre-amps should I be looking at?