Ground Cheater plug or....

I've been through all the components. The hum remains even if the ICs are disconnected from the amp. There are a lot of items in that room though: lamps, TV, ROKU box, DVD players, two seperate power supplies. The only thing I haven't tried is taking the amp to a different room/circuit breaker, mostly because I'm too lazy to haul the entire system along to test it.

RDav... you shouldn't assume that because someone is using aftermarket cables that they foolishly dropped a mortgage payment on them. There's nothing "uber" about my PCs, but at about $100 bucks they were an audible improvement over stock cords. Sorry if your hearing isn't that good. Maybe you should take up knitting.

speakers are 89db Spendor S8e. I can only hear the hum from the listening position if there is no ambient noise - i.e. the fridge is not cycling - or if I'm standing right next to them, but not when music is playing. I sent the amp in for service and Cary said this was normal, but I'm not convinced. They said they weren't able to duplicate the hum.

The plot thickens. I took the amp to a local tech who a) could not duplicate the hum and b) could not find anything wrong with the amp - although he did say it sounded very nice. Not quite believing it, I went and listened for myself, and he was right.

So, since that is now two places - Cary and my local guy - who've been unable to duplicate the hum, I guess that points to something in my AC system causing the problem.

So now what? Dedicated line? turning off the fridge is not an option.

In addition, I figured out which circuit the hi-fi is on, turned everything else in the house off, as well as unplugging everything else in the room, and the amp still hummed.

I also used a ground tester and the outlets were showing that they were in fact grounded.

grrrr.

So here's what fixed it. I switched pre-amps, and suddenly the amp was quiet, but when I turned on the pre-amp the hum came back. It had mysteriously jumped between components! To finally get it to settle down, I stuck a cheater plug between the pre-amp and the power supply - the PS is still grounded at the wall - and that fixed it. I don't hear any sonic degradation from the cheater. Cheaters seem to be controversial, but at this point, and since the PS is still grounded, I'm not arguing. But hell's bells. it took a year to figure out.

Well again, the power supply - a PS Audio something-or-other - is still grounded. The cheater is between the preamp and the power supply, and the power supply still has a protection circuit, so I think the risk is pretty low. The amp, which is the big power draw, is still grounded.

I might check on the polarity thing though. It couldn't hurt.

I didn't check the cord, but I did switch out my aftermarket PCs with the factory stock, in various combinations, and the hum remained.