I have an idea that may or may not help.
The big change in electrical here is the Soundlab A3s power supply which plugs into the wall, providing an additional ground plane.
The Tube Research is typically not grounded, (my GT 400s were not). However, the back plate on A3 Soundlabs tie the third pin (ground) of the IEC, and the amps neutral to the power supply.
It might be possible that this additional ground plane was scraping off noise and hum. To test, use a length of ordinary zip cord between true ground and various pieces in your system. The third pin of the wall plug is ideal and may be tested by hooking up ONLY the ground pin and then touching it to the various components.
If you have any doubt at all as to which pin is ground or lack experience with electrical, dont try this. I dont want to be responsible for anyone getting hurt.
The big change in electrical here is the Soundlab A3s power supply which plugs into the wall, providing an additional ground plane.
The Tube Research is typically not grounded, (my GT 400s were not). However, the back plate on A3 Soundlabs tie the third pin (ground) of the IEC, and the amps neutral to the power supply.
It might be possible that this additional ground plane was scraping off noise and hum. To test, use a length of ordinary zip cord between true ground and various pieces in your system. The third pin of the wall plug is ideal and may be tested by hooking up ONLY the ground pin and then touching it to the various components.
If you have any doubt at all as to which pin is ground or lack experience with electrical, dont try this. I dont want to be responsible for anyone getting hurt.