In response to the CD comparison between the Sony and the Oppo. Feeding the Sony through the Benchmark seems to sound the best but it's splitting hairs, the DACs in both the Oppo and the Benchmark sound fantastic.
Ah the HUM! I have SOLVED the hum issue. I traced every component and connection and it turned out to be the audio feed in from my digital cable tuner that was the culprit. I liked to listen to concerts on Palladium. I now route the sound through my computer and into the Benchmark, NO HUM!!! Also working with the gain switches on the RM-9 helps. I keep it set to med and it sounds great. Truly a class above the rest this tube amp, no question...