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"Also my hum disappears if I short the inputs"

Posted by JJ Triode on July 8, 2012 at 11:34:46:
This is a clear indication that the hum does not originate inside your amp, so there is no need to redo the internal wiring, etc.

Maybe you do have excess gain due to too little negative feedback, as others posted. If your feedback circuits are all correct (I believe this amp has several local as well as global FB loops) and you still have more gain than you need, an effective kluge to reduce the hum would be to put a resistive voltage divider just inside the input jack of each channel of the amp.

This won't help the microphonics, but you may get some help there from using tube dampers (I like Herbie's Hal-O products.)

Other than that, you could check if your preamp has excess hum, or try some better-shielded interconnects.