how dangerous are floating ground amps (old Supro)

[HTH]

last step - only one way to fix the isolation tx onto the chassis where it'll fit, but it means that the PT and OT are close together and they're coupling magnetically (i.e. hum).

I've shifted the OT further down the chassis to where the best spot was for lowest hum.

The last thing I'd like to improve is the heaters - any ideas?