Stick it on a speaker stand, to decouple it ( acoustically) from the floor joists.

Ya might try just getting it off of the big soundbox ( orange crate).

If it's older, try unplugging it for several hours ( to allow cap charge to disappate) and tightening up the transformer plates- they'll loosen over a few years.

Also worth checking to see if you're hearing overvoltage @ the trans due to insufficent bulb resistance- ie, cheap or old bulb. Will accentuate 60hz.