Are the amps supposed to change in your house?

Your amperage will fluctuate all the time depending on what you have on. It will go from 0 to the maximum of your main breaker. Your voltage shouldn't change much if you live in a first world country. If the voltage is fluctuating more than the equipment you want to run can handle, consider a solid state voltage regulator for that equipment. You don't need one for the whole house, the coffee maker and the refrigerator don't need power that pure. You're fine. As far as the stereo is concerned, heck, who knows? Transformers can sound like that. So can powered speakers. Could be lots of things. Where is it coming from? The unit or the speakers?

BTW, here's a nice little unit that a buddy of mine owns. Nothing too fancy:

http://www.onecall.com/ProductDetails.aspx?id=1006...

It won't power an awful lot, but the power is pure, baby.

Yes indeed. Amperes are the primary measure of current flow. If devices turn off and on, the current changes. When everything is off, the current is zero.