@carlsbad2 I will defer to you and others on the technicalities of the MU2. John Lavorgna in his review states: "I let its internal analog preamp take over for the internal preamps in the review Triode Evolution 300 and my beloved Leben CS600 and I didn’t feel as if I, or the music, lost anything. In fact there was an added clarity and transient speed that I preferred with the MU2 in charge."
Grimm calls it a "relay based analog volume control".
I use an apple remote to control the volume. When I change the volume, I hear the relay clicks just like I used to hear on the Ayre KXR preamp which I owned many years ago.