say the Pass Labs X 250.5. I used it in single ended mode, which I was told later was not optimum, although I never read that in all of my pre-purchase research. I bought it and auditioned it with 5 different speakers in my system, and in each case, the sound was thin and electronic. It was a really shocking disappointment.
Here are some units listed which are absolutely the opposite from sound quality what is written in their "reviews".
The golden rule is, EVERY unit gets a positive review, be it awful sounding or good sounding. The vocabulary will be the same (and is identical). Blind buy is really dangerous, the majority is really down at the docks....
When I did own Pass units I was sitting in a Demo listening to the latest Pass amps, at that time it was the "X" series and it was exactly as described. Ultra boring for me, so unbelievable dead that I could not believe that the same guy made the outstanding Aleph amps. Anyway, left side was a Pass Fan and he asked me what I think about those super-duper-reviewed amps, I lied and said "amazing". He loved me from one second to the next, smiled and told me his impressions about the "super soundstage", the "holographic detail" and so on and that they are M-U-C-H better than the model before (which I also knew very well). When I listened his explanations I really was interested to know what he did smoke that made him speaking about abilities which were simply not present. I mean, I was right beside him.
You see, there is a Fangroup for everything out there.