Comparing Pass amplifiers to a couple AR tube amplifiers and then saying they sound lean doesn’t really prove the argument that Pass .8 amplifiers sound lean compared to most mainstream solid state amplifiers including Luxman, in my mind at least.
Yea, I’ve owned a PrimaLuna integrated amplifier for a while when I owned Cornwalls 3s, and an all tube Mystique preamp too to try with my solid state amps, and both had and added lots of warmth and a fuller sound than either my XA250.8 or XA30.8, but I don’t find that unexpected or that they also would not have a fuller sound than C900+M900 Luxman combo I listened to.
The class AB 150.8 is like 15 watts class A; if you want to hear the fuller sounding Pass listen to the XA.8 models.
My Classe CA300 was very smooth and powerful but I don’t remember it being as full sounding as my 30.8; I never got a chance to compare them directly. I’ve heard Sugden amps over the years that have had a nice full sound.
If my 30.8 is lean, then it would be interesting to hear how you describe the sound of say the Benchmark AHB2 :)