Sound conundrum with video game footage

I'm reviewing an old Sega Mega Drive / Genesis game and have lots of game footage that I've imported into a new project that I originally acquired using a DVD recorder. I also have a voice over in AIFF format recorded in GarageBand.

My problem is that because each clip from the game has its own background music, trying to build the show is proving a nightmare because none of the music aligns and is really disorientating. I don't just want to mute the clips as there are important sound effects (baddies dying, character sounds, etc) which I want to preserve.

I'm new to FCPX (and video editing in general) and am wondering how people would tackle this problem.

Thanks in advance,

Separating sound effects from music in a baked-in audio track is going to be next to impossible. You may need something pricey like iZotope RX.

You could try things like EQ, noise gate, but basically, you will be doing a lot of manual keyframing of levels and such.