Help I think my AC is polluted

Thanks for all the quick responses. I'll try to answer all your questions in order.

Kr4 - Presently I don't really have a way to run the system on battery power. If I go in that direction, is there a product on the market that can power my entire sytem?

Nsgarch - Yes. It occurs whether using the CD player or tuner as the source. A power regenerator may be the answer, although I'd rather go to the source of the problem. I've also read that a power regenerator may inhibit current flow and dynamics depending on the system. What did you find with the ExactPower.

Tbg - When I have the hum, nothing I do can change it. What makes me pretty sure it's dirty AC from outside the house is yesterday I disconected everything from the Equi=tech and still had the hum when I put my ear up to the conditioner while powered up and on standby. Today it's gone and the Equi=tech is dead quite. I'm not quite sure how to scope a line. Can you give me more info on that?

Stilljd - You may be right about low voltage. I've been living here for six years and we used to get quite a bit of power surging. I would often see the lights brighten and dim at night. I haven't noticed this recently though. I will complain to the power company and see where it gets me. The odd thing is the hum happens on the weekend and that's when the power grid should be cleanest. Unfortunately, it's also when I have most free time to listen to music.

Hotpanley - I will try your suggestion but given the two week intervals between this problem, I'll be surprised if it's something within the house.

I appreciate all your responses to help solve this problem.

Happy listening, Mike

Zargon - Thanks for the informative post. What is the cost of an isolation transformer such as the Topaz? How much work is it for an electrician to install? I had one hell of a time getting an electrician to do two dedicated lines. Would this be a better/more cost effective solution than a power regenerator?

It appears that an iso transformer may be the answer to this problem. From what I've read, the iso transformer will take care of external AC noise, voltage fluctuations, and DC finding its way into the house. I'm first going to call the power company and see if they can do anything. Does anyone know if there is a maximum allowable voltage swing that the power company must maintain within established limits for residential applications? If the problem is DC finding its way in, can I hold the power company responsible for rectifying the problem on the assummption that its a safety hazard? I'm guessing this is a somewhat unique problem given that it occurs intermittently.

Thanks for all the helpful responses.