Thank you for such a thorough and thoughtful response. As you said, my expectation should be tempered in accordance with the nature of tube amps, which tend to be more noisy than solid-state. And yes, I know that some tube amps are more noisy than others, my curiosity is just whether the reputable Joule/Merlin combo is as noisy as my setup has turned out to be.
Last night while listening to Stevie Ray Vaughn, Sigor Ros, and Miles Davis; I was again struck by how deeply I can hear into the recording, but it was only during the very delicate parts of the "Round About Midnight" Miles SACD that the hum bothered me. Unfortunately this is heard quite predominantly during classical music, of which there are so many delicate and quite parts, so that is a bummer.
My DC Offset seems to be reading normal. I usually check it every couple of days just to make sure that it is not at 0 or 1 (it seems to be anywhere from 5 to 40) and I wait until the amps have been on for at least an hour, before checking. I have experimented with the feedback controls, the variac settings, and the bias, all in order to fit my room and my musical tastes. I keep the amps between 64 and 65, the output tubes around 27, and the input/driver stages close to 120. My feedback is set to around 7 or 8 o'clock, depending on whether I am in a more musical or analytical mood.
I have been in contact with another Joule customer, with a similar system, who is experiencing the same thing, so I will update you with our collective findings. He took delivery of his Joules in December (mine came in October), so maybe it is a current tweak from Jud that is not working out as planned.....or not.
Updates to follow. Thanks again Rich.
-Jake