Wow, I do type slow..
Now, if it were an FM problem, it would manifest itself at all volumes.
Anyone else have any ideas here?
Mark brings up several a good points.
Just to be sure, double check for the noise at lower volumes.
I have a feeling it's there, though just not as noticeable at the lower volumes.
Another quick and free test: switch the receiver to mono, does a good part of the noise go away?
If so, get a better antenna.
Had a similar problem, I get mediocre FM reception here. When I first bought this house (15 years ago) I put up a large TV / FM antenna and a rotor, and the difference was unbelievable.
With the cheap dipole antenna that comes with a receiver you will pick up all the electrical noise from inside the house. That along with all the multi-path noise.
Unless you can get a good signal bounced off of a nearby building or mountain, FM reception gets better, the higher up the antenna is.
Meaning a roof antenna, as TLS Guy mentioned. You may be able to get away with an antenna in the attic, though it's not ideal.