Originally Posted by 1Time
Which seems to mean the uAMP107B should not benefit from the amp in the HotUSB1 and should only benefit from the DAC in the HotUSB1. If so, that's news to me.
Huh? No. You're not understanding.
Anyway, like I said. Ignorance is bliss. I can clearly hear clipping with the uAmp107 and my HD650.
It's clear to me that you don't know what clipping is or how it manifests audibly. Might I suggest some reading.
Clipping (audio) - Wikipedia, the free encyclopedia
It has a picture too. In a way, it's a form of dynamic compression (it's not, technically, but I have no way to get that through to you). You can make the quieter parts louder, but you can't make the loudest parts louder. It's a wall, but there's distortion once you hit the wall.
Originally Posted by 1Time
If only what I'm hearing with my HD580 would convince me that any of this matters.
That's fine. Either you don't know what you're hearing, or you don't listen to stuff as loud as you think you do. It's as simple as that.