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

In my observation, those whose hearing is good enough - no need for golden ear - hear very similarly but they can verbalize it in a different and sometimes unclear ways and of course, sound preferences differ. Most of people around me prefer electrostatic speakers, as an example, and I don't. 
As for the Pass gear, it doesn't appear to be for me, regardless of certain fine qualities that it has. I wouldn't consider Bryston or Sim Audio either. I would skip all that and go straight to Gryphon or some Swiss gear for transistor sound. No idea about Italian or German electronics.

Pass amps very good not quite as good as WADIA but probably equal to McIntosh and krell. 

I have an Aleph 3 in storage now. It is sweet and delicate sounding but when I moved to a larger room it didn't work and maxed out below listening levels. It also runs warm and lacks bass punch and dynamics. It is transparent but speaks softly. I've never had high efficiency speakers but with the right speaker and a smaller room that amp could be magical.

My phono pre is an Aleph Ono that I've had for years. I find it very neutral sounding with good stage depth and imaging. It is also very quiet and has balanced outputs.

I've heard an XA200 and it was stunning. It had the same delicateness of my Aleph3 with way more dynamics.

Like a lot of audio equipment, living here in Vermont, I haven't had a chance to hear a pass amp.  But I think you can pretty much summarize from this threads lack of comments on their weak points, that most everyone is positive (very ?) about them. The class A heat being an obvious, to be expected, point.  There were just a couple of outliers.

As a new owner of a pair of 260.8's and still in the 'new car' stage I can appreciate a number of the responces you have gotten. I moved from a ML333 which I liked very much to the Pass. As far as weak points, I have yet to hear anything that I would consider a weak point but again, I have had only one or two days of serious listening thus far. I do like the way vocals seem to be handled as to me, they seem to convey a in the room sound, very realistic .The bottom end is controlled and very responsive without being 'in your face'. 

I have tried several genres and have, as yet, found anything they do wrong. I feel that is a good step up and I find myself enjoying music that I have not listened to for a while because I felt that the recording was not very good but details are far more layered with the Pass.

Yes, they tend to get warm, but as far as I am concerned after 8-10 hours no more than the ML. As there are now two I have noticed a slight increase in the room temperature (it is winter after all) I will have to see how they do this summer, but not terribly concerned, the sound out of them is worth any inconvience there