Just an idea, I had a hum problem with my center channel and mono amp for driving it. I inserted a Jensen Iso-Max isolation transformer in the interconnect, and 90% of the noise went away. It might be something to try. I have a two-channel analog set up (using the same main speakers, separate tube preamp and SET 300B amp) with no noise issues.
Hope you get it sorted out.
Regards,
Dan
Hope you get it sorted out.
Regards,
Dan