I recently purchased an X250.5 and love it. I've seen several amps go through my system over the years including an X250 and an X350. I've never felt content with my amp and always felt the desire to try something different although I really enjoyed the X350 better than any other I had had at the time. But I doubt the X250.5 will be leaving my system for quite some time. Every time I sit down to listen, it seems to sound better. I would strongly recommend a listen to the X250.5 or the X350.5. I can't really imagine the X350.5 sounding a lot better than the X250.5, but I was surprised at how much of an improvement there was in the X250.5.
New Pass Labs X.5 series versus previous X series
Pass Labs is in the process of re-dedesigning their entire X series into the new X.5 series. As of this writing X150.5, X250.5 and possibly X350.5 are already shipping. The X600.5 are expected to start shipping early in the new year. This thread is to discuss experiences with the new amps, their sound signature, perceivable improvements over the old series, and of course dissenting opinions. Everyone's perspective is welcome--X and X.5 owners, X.5 window shoppers, Dealers, and all other audiogoners with a passion for affect by the bug of audiophilia.