60Hz Hum in Mesa Boogie Triaxis

[rf7]

Anyone ever ran across this issue with these? I grounded the returns and it still hums even though it's only going thru one tube's gain stage.

[rf7]

OK, I found you have to plug into the send to lift the outputs from the front of the amp.

I lucked out, it turned out I found 3 tubes that were the culprits. The first thing I did when it came in was swap tubes and it did not help. One of the new ones must have been humming.