Line conditioning products that work are going to cost money. It sounds like you really should invest in some type of power conditioner. Go to one of the mass merchandisers, like Circuit City, who offer 30 day no questions return and pick up a Monster Cable multi task unit, around $350. and give it a try. Some of these types of products offer adjustable frequency, I would not recommend messing with that and NEVER change the frequency of your outlet power going to your turntable. Turntables are made to work at 60Hz and any variation has proven to be disastrous. It sounds like you would most benefit from voltage stablization but that is very expensive and debated how effective these products can really be. Monster is a good starting point, I wouldn't go any cheaper than that and everybody's power situation and interferences are going to be unique to their own area, so I would recommend trying any product before you buy it to see if you gain anything for your money.