Are there any people who know how to tweak an amp just when you want to get rid of vibrations? I mean damping the transformer by taking it out and put in on rubber or something else, or gets a transformer to hot for it? Can I damp elko's too? Or maybe the print circuit board?
If you have a noisy amp tranformer, contact the manufacturer for the best way to fix it. If you have a ground loop hum there are several options. Hum is usually caused by differences in ground potential in connected electronic gear. The easy fix is to get a balanced power conditioner, but do your homework as some are overpriced and have their own hum problems. The cheaper solution is to find the offending piece of gear and replace it. Sometimes it just requires you replace a bad cable. Do a google search for "ground loop hum" and you will get all the advice you need.