[royal]

Hi everyone, I have an Outlaw model 750 Amp (sorry couldn't find easy link as it is several years discontinue but it is a beefy 50 lb 5 ch HT amp.)  Long story short - i have been using it since new as a bi-amp for the speakers in my two channel system.  I decided to upgrade everything and while waiting for my new amp the Outlaw develops this hum - hmmmm - coincidence?  You be the judge.  Anyway the hum us audible 10 ft away when everything else is quiet -even to my elderly ears, not loud, mind u, but definitely audible.  On tracking it down (by placing my ear next to the 750)) I discovered it is coming from the amp itself .  The hum is unchanged even with no inputs or outputs hooked up.  I should mention that I have just completed moving my whole A/V system to a new room. - coincidence?  I don't hear it in my new Outlaw processor/pre/power amp setup right next to it.  Any ideas (non supernatural) on what would cause this?

[mcgsxr]

Could it be a ground loop?  Is there plugged into,the same AC outlet as the amp?  What electrical changes were made to the room?

[Doublej]

Since you've said that it occurs without any inputs or outputs I'd unplug it and put it back into the outlet where it was in the old room.

If the buzz remains it's likely the unit. If it goes away then you have a problem like as mcgsxr says a ground loop or something interacting with the unit causing it to buzz.

If you are comfortable with taking off the cover you could unplug the unit, remove the cover and then plug it back in to see if you can identify by ear what component is buzzing. It's possible that the transformer screws need tightening or something got loosened in the move.

Be very careful as you can zap yourself even though the unit is unplugged. Capacitors can retain a charge for a LONG time. You've made it this far in life. You don't want to become a Darwin award winner.

[Speedskater]

If it's a mechanical buzz and it still happens with all the interconnect cables removed, it's not a ground loop.
It's either power line related or it's just plain mechanical. Lot's of big power transformers with loose parts buzz.

To check the power line part, take the amp to a friends place and see if it buzzes. (not your neighbors)