Mechanical hum happens because the transformer is working a little harder to provide the correct current to the gear.
See if you can borrow an issolation transformer or one of those PS Audio power regenerators (or similar). These will provide the correct current to your gear, and will allow you to hear if the hum goes away.
The above are a solution to mechanical hum. Sometimes though the transformer in this piece of gear will hum a little because it is getting the outside power. Better one than all the gear. It can always be muffled away if this does happen.
See if you can borrow an issolation transformer or one of those PS Audio power regenerators (or similar). These will provide the correct current to your gear, and will allow you to hear if the hum goes away.
The above are a solution to mechanical hum. Sometimes though the transformer in this piece of gear will hum a little because it is getting the outside power. Better one than all the gear. It can always be muffled away if this does happen.