From the sounds of things you might just simply try a different, yet better microphone. SM57's are OK at best but there are much better mics to capture guitars. Then again, sometimes only a 57 will capture the guitar cab correctly but 57's have been hit or miss at best in my experience and it depends on your playing style and how much "woof" or low-end mud you have going out the speakers. Someone said earlier in this post, "I know you've heard this before, but the mic doesn't hear things the same way our ears do." There's half of your problem right there. Try a different mic that picks up the amp more like your ears do in the room and you've licked half the battle. Trust me, there are MUCH better mics than 57's to mic with. I'd say start with a beginner's ($99-199.00) large diaphragm condensor mic and you might be pleasantly surprised or then again you may be sorely disappointed-depending on exactly what you're looking for. Just be sure to get your mic from a store that has a no-hassle return policy so you can try out different mics for a few days or a week to be sure that you'll be pleased with your purchase. I've used an MXL 990 before when an SM57 didn't seem to be getting the right sound. Now I know the 990 isn't the best LD mic in the world but between it and an SM57, I can accurately capture the sound of the guitarists I record. Then again, that's just my opinion based on personal experience and I could be wrong.