Mechanical buzz coming from the chassis

Sounds like tha amp is acting normal during operation if you have to place your ear that close to hear transformer hum. If it still bothers do what newbee suggest and also placing the amps of something soft if on hard surface. Placing them on a rubber mat does help.

I checked the screws on the power transformer, they were loose. I tightned them and the hum is nearly gone. I really have to get my ear in close to hear it now.

Do I need to be concerned that there is an underlying problem with the transformer or incoming power? I have a dedicated 20amp line for the system so there is not much I can do to improve the power.

This is a matter of degree - so how close does your ear need to be to hear this ?

I had the same problem with my Quicksilvers. I called and was told if the amps were on a shelf I should put carpet underneath amps which solved the problem. I bought a set of isoblocks (cork blocks)and put them under the feet of the amps and they work great. I think that should have been mentioned in the owner's manual.

I have the amps sitting on 1/4" thick cork mats. This helps, but regardless the hum is not audible from my listening position.

The other strange thing is that only one amp hums but both amps had relatively loose screws.

Also, soft mats and tightnening screws will eliminate the symptoms but do not address the root cause.