Class A\B or D for summer months (vs Class A)

@tbac23 I listen to a class D amp year round. I'd put it up against any Pass Labs amp with no worries. It replaced a set of class A tube monoblocks and I've not had any reason to look back.

But you might also consider that if your amp makes heat there's a simple way to move it out of the room without air conditioning. If you can place a vent in the ceiling above the amp, you can used dryer hose and a small fan to vent warm air out of the house. That's a lot cheaper than air conditioning. Works best if the vent is directly above the amp.

I agree with keep your amp (I'm a Pass XA owner) ands work on a/c ventilation issues, it could be rather simple...for myself, and everyone I know, Pass and Benchmark sound quite different...though some do prefer Benchmark...

@tbac23, I had in-room heating issues in the summer with my XA30.8 and swapped to the (very) cool running AtmaSphere Monos and I found the sound signature between the two amps to be very similar.  e.g. no fatigue, nice midrange centric presentation with lots of midrange texture.   The Coda S5.5 with 50w Class A runs cool compared to the XA30.8 at least and is more neutral and resolving to my ears (and way more dynamic), but is likely out of your specified price range.   I also owned an AHB2, and although I liked it, at least compared to the warm and cozy XA30.8 I didn't think it was that similar sonically.   I've never heard the XA25, but if it is less warm and more resolving than the XA30.8, then at least it would like be closer in signature to the Benchmark.   

I went through the same process with the addition of tube replacement cost and weight.  I ended up with AGD Audions. I could not be happier.  I did retain my Cary SLP 05 tube preamp.  I would consider a used pair of AGD’s or Atmosphere class D amps.   Try to here before you make a final decision. 

I have to second the notion of using the available funds to fix or supplement the AC. I had the same issue in my office where I have my headphone rig. I have several tube amps there which all give off quite a bit of heat. I would have never even considered switching to SS or something of the sort, but that's just me. In your case, I feel like you heat problem will remain even if you change amps. If you notice any difference, it likely won't be enough.

In my case, it turns out the main return was undersized for the house. I guess they didn't do the best job at calculating those 20 years ago. I added an additional small return outside my office door which is in the opposite end of the house from the main return. I also added a larger dedicated run to my office off the main duct and installed a bigger vent. If this hadn't worked, my next move was mini-split.

On the other hand, a new amp to switch things up for a few months out of the year sounds like fun too. Best of luck with whichever path you take!