For anyone who may be wondering how close the emulator sounded to the actual games: I recorded songs from the emulated versions of "beatmania GB 2" and "beatmania GB Gachamix 2" and compared them to the recordings I made form the actual games – I couldn’t find much of a difference (the emu version had stronger treble, but that’s about it.)
EDIT:
It turns out I posted the same link for all three files, when I originally created this thread. Here are the correct links:
beatmania GB OST:
beatmania GB.zip (http://www.mediafire.com/?5xodmd6b3adv2wf)
beatmania GB 2 OST (a.k.a., "beatmania GB 2 Gachamix"):
beatmania GB 2.zip (http://www.mediafire.com/?38dv9m4acubn0dm)
beatmania GB Gachamix 2 OST:
beatmania GB Gachamix 2.zip (http://www.mediafire.com/?24rabbaoau8z8jk)