One more note. If you do tilt you amp back so it's going towards your head, it might be a shock to you, to actually hear what it sounds like. When/if you do this, remember that that's more than likely what your audiance hears, so adjust your settings for that. It probably wont sound very good at first, and can be a bit tricky to dial in right, but this is what you need to get used to if you play live.

Another trick you can do is to put some duct tape on your grill cloth at the center of the speaker. Make you a circle of duct tape that's about 3-4" in diameter and place it directly in the center of each speaker on the grill cloth. This will spread out the piercing highs and disperse the sound a little better. It's a cheap alternative to >these<.

Also, if the back of you amp is sealed, try removing the back panel, and make sure the back of the amp isn't right up against something. This will also help spread out the sound, and make it more 3 dimensional.