Stereo mic your amp! Place one mic close to the grill at a 45 degree angle on the left, and another mic farther out in the room, at least two or three feet, facing the grill at a 45 degree angle on the right. This way, the sound from your amp hits each mic a few milliseconds apart from each other. Pan them hard left and right, respectively, and viola, you have a stereo recording. Make sure when doing this you don't get any phasing. Keep each track in the middle and solo each, when combined the level should increase. Also, listen for distinct phasing, reminiscent of a phaser pedal. The rule of thumb is to have the second mic at least three times the distance from the amp as the first mic, but you should check with your ears either way.