When you turn your twin amp on the transformer hums even without the stand by switch on Should you replace the Input transformer?

Before you spend that kind of money, try the simple things first.

If the transformer housing is bolted together and/or bolted to

the chassis of the amp, tighten all the bolts.

Even if there are no bolts visible, do some experimenting with

a strong clamp: With the amp turned on and the transformer

humming away, go around the transformer housing and apply

the clamp to it, carefully, in various places and in various directions.

You may find a place where putting the squeeze on it either stops

or reduces the hum.

One other thought: A humming transformer can be an overloaded one.

If the transformer gets extremely hot after the amp operates for a

while, and especially if smoke ever comes out of the amp, then the

humming is a definite clue that there is a problem, but the problem

is not the transformer.