RFI from steel TV bracket?

My first thought is; it's not the rack but the TV. Try lifting the ground to the TV. Or possibly pluging the TV into a known different circuit that is on the opposite phase of the balance of your system. One other suggestion if you feel it is the rack, can you put the old TV(if you still have it) on the steel rack and determine if it is indeed the rack. And fiannly I assume you have tried unplugging the TV to see if the hum diminished?
I have been down this road and you just have to try every possibility to find the gremlin. Good luck.

Yes I unplugged the TV and also tried it in different GPOs.....even a power conditioner. I even disconnected the 'sound-out' of the TV from the preamp. Hum still there.
Interesting thing is that the hum is from the amps and not the preamp as when I listen to my headphones which are plugged into the 'tape-out' of the preamp......no hum?

Possibly, the interconnects to the amp aren't shielded and picking it up(?) or, if this TV is a Plasma, they do give more interference.

Last TV was plasma. No hum.
This TV is LCD......hum.
But it hums with the TV completely unplugged so I don't see how it can be the source?

Ground loop from your cable tv or sat box. Unhook the coax cable from the source tv direct/cable box or sat and turn everything else back on and take a listen. Tom