What are the weak points of Pass amps and pre-amps ?

Though there are perhaps better transistor amps, but Pass seems to be an excellent choice for many.
What is your experience with them, if you could elaborate ? Integrateds as well.
I owned the Pass XA30.5 and it put out very little heat into the room going 24/7.

I now have a pair of XA60.5 going 24/7, and do not notice a rise in room temp. I have the amps on 2 Inch maple boards. Electric bill is up about $30 per mo. when on 24/7.

Pass Labs gives me SOTA sound quality! Could not ask for more.

I like a dead quiet room, so I shut off heat or A/C when listening.
I'm with Jetter as someone hooked on tubes who wishes people would stop raving about the XA25...please stop...I don't want to get rid of my single ended tube amp...but the existence of the XA25 is taunting me...I'd appreciate it if somebody would pan that thing so I could stop wanting one.
Sorry, @wolf_garcia, but the XA25 is the best amp I've used in my system. I've used: CJ MF2550SE, ET250S, Musical Fidelity SS.

What I love about the XA25 is that I get >wonderful midrange from the CJs with most of the bass slam of the MF SS. The XA25 has the best soundstage of all from my Sophia 3s.

But no, no real downside to the XA25 except that it doesn't have the bass authority that I've heard from other amps.

Well, another downside is that my other amps only get used in my office system or are in the closet waiting for adoption to a happy home.
Well you asked so here is my opinion. I owned for quite a while the Pass X350.5 amp and the XP-10 preamp.

The XP-10 preamp to me was average. The step up from it was the XP-20 which has 2 separate chassis, I never heard this unit but I didn't like having to use extra rack space for the units.

I compared directly the Pass X-350.5 to the newer XP-350.8. I just did not like the newer X350.8. To me it sounded much more closed in and had less treble presentation than the older 350.5. Caution either chassis gets very hot! 

Eventually, I tried an Atmosphere M-60 3.3 and sold the Pass. Today, I own the Bob Carver Raven 350 tube amps.

Each step improved my audio enjoyment as I moved away from Pass.

Jetter, I own an XA25. It’s cheap in that it punchers wY over the specs and is brilliant.  I also own their pre XP-22.  Have had XP10 as well. Very good equipment.  There is nothing bad here.  I came from mostly Reference level CJ TUBE equipment.