sorry, I'm a bit behind on following this thread.
I just want to make a comment that my UMC-1 has significant audible "hiss" running through an XPA-2 to my LaScalas. The hiss is obviously much reduced when I play through my Herseys or my Polk RTi-10s. The "hiss" is heard on all input (HDMI, analog, stereo/direct modes, etc.) and is a constant level. Also, you can hear every "click" such as pressing the mute button, when a CD track changes (UMC-1 unlocking then locking onto the signal, etc.).
I do not believe anyone on the emotiva forum is running a UMC-1 with Khorns or LaScalas (104db..) so I am very interested in your post of a totally "silent" UMC-1 experience. Maybe I have an actual "bad" UMC-1 unit. I have Lonnie (over at Emotiva) running some tests - or at least he said he was.. regarding the "hiss" I have reported to him.
Other than the "hiss", I believe the UMC-1 (following the 1st firmware update), is a great piece of hardware considering it's low entry price.