I've had good results with an RE20 straight on at the dustcap, from basically as close as I can get it without the mic touching the cap when it moves. It's a cool sounding mic. That was on a Marshall JCM2000 (yes, guitar head) driving an Ampeg 4x10, with an adjustable tweeter turned off and the highs on the amp blasting so that the speakers still have some brightness to them without dealing with near as much fret clickiness. However, more recently I've had really nice results with just a Radial Passive DI, with a nice Schecter bass with new strings on it. The new strings are a must, though.