Pass X250/350 /Plinius SA250/Classe CAM350's/Sim

I am seeking to upgrade my amplification.

My current setup-

CD- Cary 303
Pre- ARC LS12
Amp- Classe CA150
Spkr- Proac Response 2.5's

While I am generally satisfied, I have a bad case of "upgrade-itis" and the family CFO (my wife) has given the OK.

I've been considering the following based on my research (I am located in arural area, so demoing is impossible- listening at dealers in the course of my travels is unreliable at best)-

Pass Labs X250 or 350
Plinius SA250 mkIV
Classe CAM 350 monoblocks
Simaudio W10 monoblocks

Sorry, I'm just not a tube kind of person.
(I am also considering going to the Proac Response 3.8"s in the future, so the amplifier needs to be OK for those as well.

Any ideas/insights are appreciated.
From your list I would recommend either of the Pass X series models. I have no personel experience with the others you mention; so I can not comment. You may also want to consider the Conrad Johnson MF2500A it is 250 WPC and very comparable to the PASS X250. You did not mention if you are considering used. If you are there is a good selection of Pass and CJ on Audiogon right now at very good prices. If you are only considering new, and as you mentioned you live in a rural area, you may want to discuss with the variuos dealers the possibility of an in home trial period.

The Pass amps are superb, and WILL mate nicely with the Proac 2.5's. The Plinius and Sim's are very good, if a hair behind the Pass's. Then the Classe Behind those.
I used to have Classe CA150, as well as Audio Research LS16 preamp driving some Thiel 2.3's. My system WAS similar to yours in a lot of ways. I upgraded amps to even a used Threshold T200, which was superb for cheap used ($1600). I used to sell the Pass, and Classe Stuf, andy my buddy owned the Plinius 250...I've heard the Sim.
It's all good gear, but I'd give the Pass a nod over the others, then probably the Sim, then the Plinius,then Classe.
Good Luck
Have fun
For what it's worth, I've been using a Pass X-150 with ProAc 2.5's for the past 18 months, but I'm now feeling it's time to move on, possibly to Plinius or Chord or something else. The X-250 or 350 might be a different story, however.
I have had the Classe 350's for about 18 months, driving inefficient speakers, and they are truly wonderful. They are a step up from the Pass Aleph amps I had before, but I understand that the Pass X series is also. One thing you might consider is practicality: the Classes weigh 75 pounds each, so a moderately fit (is there any other kind?) audiophile can move them without help, something unlikely with any comparable stereo amp, and shorter speaker cables are less expensive and more effective.
I have auditioned the Proac 3.8 at Goodwin's in Waltham-MA with the Classé CAM350. It was a good match. Although for my very demanding speakers (Thiel CS5 i) I preferred to upgrade my previous SimAudio W-5 with the Pass X-350.
If you want a tubey sounding amp without actually owning a tube amp, I recommend the Plinius SA-250. There are a few available on AudioGon at killer prices. I've listened to the Pass and the Classe' amps, but prefer the Plinius. I have relatively efficient speakers so I don't know how well the Plinius will perform with the ProArc's.