Can moving wire location at circuit breaker reduce hum?

So, we are talking about a mechanical hum that you can hear or feel at the amp itself, right? OK, that’s a sign of DC on the line.

If you move to another "leg" of the panel it may fix the problem but only if the source of the DC is on another circuit. See if you can locate the source which is often something like LED power supplies or some wall wart somewhere or old dimmer switches. If the problem is on the same circuit as your audio gear then no amount of moving a breaker around will fix it.

If you are sure the source is not on your circuit, then try moving to another leg. Panels alternate legs horizontally, so pick a new location that is off by odd row numbers. 1, 3, 5, 7, etc. If you move horizontally or an even number you will stay on the same leg.

Of course, they also make DC blockers specifically for this purpose.

Hi

Looks like you have a pesky one. The way you described it is a little confusing though. Does the hum happen constantly or is it “oftentimes”?  Is the amp the only component humming or are there more?  You talked about “any component that’s humming”, what else is humming?  The fact that moving the amp to another room stops the problem tells you it’s not the amp. Have you tried different outlets in the original room?  To find out if the wiring is at fault, you can try a simple, inexpensive wire tester such as this one: Klein tool RT110 receptacle tester. Moving the wire should be your last result. Good luck. 

First make sure there are no motors on that circuit. If not, then use a receptacle tester (the one that plugs in with three lights) and see if it is properly wired. Next step is to check for an unbalanced neutral at that receptacle. Measure both hot and neutral with respect to the ground. Anything more than a few volts on  neutral to ground is not normal. Also check the hot to ground voltage at all other receptacles on that circuit. Any difference is the results of loose wiring, which can cause arcing. Any of the above will make transformers sing.

When I was building my room, I was advised that "the 2 dedicated 20 amp lines MUST be on the same phase leg. Otherwise I could get a ground loop".

Is the hum present when the component is connected to amp with RCA/XLR, or just the component into the electric outlet? Because if you just connect the component to the electric outlet and no other cables are connected to that, then you can rule out the ground loop.

@milpai  That's correct but I think you missed that this is mechanical, not electrical hum. 

Mechanical hum comes from DC on the line, not from ground loops.  DC is when the AC voltage is shifted up or down by a DC voltage.  So the AC may be 120V, but it's shifted so it's 0 crossing is no longer 0.