I won't use the D2's or the D3's for anything unless I absolutely have to. The D4 however sounds pretty good on toms, but I won't use it on kick (like Audix used to advise) or on bass cabs. Maybe on certain guitar cabs though (hadn't really thought of it till now since I usually avoid Audix mics). The D6 however I find very usable on floor toms, kick, bass cabs, and even some guitar cabs. I really don't use the shure 56's since I also have beta 98's , senn 604's and 421's and vintage EV 408e's. I actually don't care for the 421's much on anything except drum percussion and brass instruments. Also, I am not fond of sm57's on toms, but surprisingly enough, I recently ended up using beta 57's on toms for a show and it worked out pretty well.
