Looking for preamp to go with pass labs x250

Has anybody compared The Simaudio P-5 to the Ayre K-1x preamps
The Pass X-2.5 and X-1 are excellent matches for the X-250 power amp, I preferred the X-1 over the Sim P-5 and Sonic Frontiers line 2. Cannot help you with the Ayre. For SS preamps the Tom Evans Vibe was a killer preamp and bettered the Joule Electra 150 (a real nice sounding preamp with the X-250), Lamm LL2, BC B-3, and a few others. I prefer a tube preamp with the X-250 to get the mid range to sound more real (I like tubes in my system) unless you get the Vibe.

Hope this helps.
I use a Pass Aleph P with mine. At this level, it's just a matter of personal taste.