I noticed when i set my Star Wars Boba-Fett action figure on the amplifier with his arms down, it produces no noticable effect, however, when i raise his arms up, it made some improvement. Then i decided to give him his Pistol and Rifle, and noticed a strengthening of the bass with tighter punch, but the mids seemed thin, but when i took replaced his rifle with his other pistol and everything sounded smooth, clean, and tight.
I've been messing around with a dead raccoon as well, what i did was lay it over the speaker cables and it seemed to bring out a little more warmth. Of course, this tweak is only lasts as long as the carcass. And sometimes the smell started to get to me, so i tweaked my nose with some vix vaper-rub and it seemed to lessen the burden of the stench.
My current raccoon set is almost used up, i need to go get some fresh ones here soon.
I also have been experimenting with a tweak that might seem a little strange. I replaced the fuses with carrots with a copper wire fed through them. I then removed all the internal circut boards from the chassis and hung them up with fishing twine. That seemed to result in a little broader soundstage and the highs seemed a little bit more refined.
Well, thats my tweaks. I'd like to hear some more of yours! :)