Happy weekend everyone, I purchased my Omega rig in 2015. Completely happy with the system (Super 7XRS Mk II and Deep

. I ordered the speakers first, Louis built them and totally loved them (more so after break in) but needed some support on the bottom. Ordered a Deep 8 woofer, received it but since our room is so quiet the low level 60Hz hum was a deal breaker. Called Louis and he swapped out the amp. Silent, no 60 Hz hum. System worked wonderfully since 2015. Now the sub amp has a hum (60 Hz) regardless of volume, x over freq or phase. Using the high level input off my Decware Rachael. I have been through more than a few plate amps in studio monitors, and I know they are not going to last forever.
SO MY QUESTION- someone must have replaced the amp in their Deep 8 with something (better) and what was it?
Looking forward to any and all advice and or comments.
Happy listening, Chris.