For sound proofing, all I've done is to have very 'soft' wall hangings, etc. I record just about everything direct, so this really isn't an issue for me. Although, I am related to some electrical contractors, and they did something for me like isolate the line or something like that (I'm no electrician) and now I have reduced hum and surges wont be an issue. As far as my guitar sound goes, I'm a real geek for old stomp-boxes. I could be lynched for saying this, but I am still in love with my old Zoom 505. When direct recording it has a wonderful clean sound, and when I go through an amp (usually a Marshall VS80 club amp) it has a distorted crunch from hell. As you know, it really depends on what you're playing. I like to tweak strange stuff, like get this: I have an old Yamaha DJX2 which is primarily a low grade DJ tool, (I bought because it was very cheap and can do some interesting sampling) and I've found that if I run my 505 into it's sample/mic port and then mic the speaker (running it into a direct line on the Fostex) I get a dry bluesy tone that the Reverend Horton Heat would approve of. I admit, I'm a real wood-shedder, but what is better than hanging out in your spooky-decorated 'studio' practicing tapping ala Buckethead while watching it rain on the Sandia Mtns.?
P.S. I see you're in Il.-- I went to high school in Joliet, Man y'all got a good scene out there. I had a couple of friends who got signed to Olympic Records in Elgin right out of their sophomore year.