I've created a MAME cheat that allows disabling TAP's in game music. It doesn't disable music playback in the sound test screen. The attached package contains the cheat alongside the TAP cheats from Pugsy's Cheats. The no music cheat works in the latest version of MAME and MAMETGM.
Neat, but it's always been possible to disable the music in MAME: just turn down the volume for YMF278B Ch. 1 in the slider controls. If you don't want to disable the music completely, you can also use those same slider controls to adjust the balance between sound effects (Ch. 0) and music (Ch. 1).
