Can moving wire location at circuit breaker reduce hum?

@ptss - Yes, unless it starts to hum instead. 😁 The output of a transformer is going to lack DC, eliminating the hum from your amp but it may just move the problem to the Equitech.

The reason DC causes physical humming is because of the laminations in the transformer. Of course, some transformers are more susceptible than others, but none are 100% immune.

My point is just that if this is significant the OP should do everything possible to eliminate the root cause first.

Knowing whether one side of the bus has a larger DC bias relative to the other would be a great place to start.
Without knowing why it is difficult to address the solution to the problem.
 

My point is just that if this is significant the OP should do everything possible to eliminate the root cause first.

So personally, I would reword ^that^ to”

The OP should do everything possible to determine the root cause first.