Help. System sounds thin and bright or harsh

A dealer suggested a failing power supply. Something is off with it for sure.

Did you call Pass Labs? 
I owned the X250.5 for many years with 3 different speakers and the only way I was able to make it sound less than excellent was by using crappy components upstream. It’s transparent enough to show you what each component is doing. 
So this sounds odd to me but I’m there and I don’t hear what you hear in your system. 

yeah audphile 1 it is puzzling to me as well. I found the same degradation in sound quality again with the pass labs replaced after a couple of hours listening. I have called pass labs or Reno hifi where I purchased the amp from (back in 2014) and they tell me I would hear something different if the amp was to blame, like clicking and that both channels would not likely degrade at the same pace. 

I can't figure out what goes wrong...just some distortion and less meat on the bones. Felt new pre and dac fixed it but then it came back (bad sound) so I took the pass labs out of the mix and things sounded pretty good still using an Oppo bdp 105 as a transport via coax cable from DH Labs. I'm bypassing the tubed output stage using digital out.

There are only two components left the Oppo and the Harbeth 30.1 speakers. Also wondering if there some type of electrical bugaboo in the house that's only 5 years old.  I am using a Puritain 156 conditioner for all components except for the pass. I felt the Puritan really made a big difference and even tried it with the pass but pass labs recommends plugging straight into a wall socket with stock cord. 

I’m also using Puritan PSM156 and I like the sound of my Pass Labs amp being plugged directly into the wall outlet as well. Could be system compatibility when it comes to how all the component interact with each other (input/output impedance, gain, input sensitivity). 

@cymivka - I have x250.8 and psm156. They work beautifully. If you're looking for preamp, I recommend LTA MicroZOTL preamp. I just got it and sounds wonderful with Pass and Falcon Ls3a/5, which tells me it would also work well with harbeth.