I agree with Stringreen that I have never heard a power conditioner that didn't do damage to the sound, especially analog. Perhaps I am lucky with the power in my area, though, as in my brother's area, a power conditioner results in a distinct improvement.
However, a surge protector is a must if you live in an area with frequent storms, as I do. I like the Monster ones, that basically don't do anything at all to the sound, yet protect the equipment. Basically, they fry themselves in the storm, protecting your equipment. This has happened twice to me, and both times it worked exactly as it was supposed to. You can get them very cheaply on Amazon.
However, a surge protector is a must if you live in an area with frequent storms, as I do. I like the Monster ones, that basically don't do anything at all to the sound, yet protect the equipment. Basically, they fry themselves in the storm, protecting your equipment. This has happened twice to me, and both times it worked exactly as it was supposed to. You can get them very cheaply on Amazon.