BS Zelda The Third Quest

I have been stuck with this game trying to find out exactly where the audio changes when entering/leaving a cave,dungeon, etc. The game goes into so many loops, it is difficult to find where exactly the code write to the spc port to start/stop the tracks.
I already figured out how to swap in the pcm tracks for the title and player select screens but cannot go any further. Any clues?

You somehow posted it in the database for finished patches, so I moved it...

The code for tracks change is VERY easy in this game:
$C5/BED2 8D 40 21    STA $2140  [$00:2140]   A:0301
Here 01 gets directly into audio port 2140 to play the overworld music, e.g., when leaving a cave or dungeon.

$C5/BED2 8D 40 21    STA $2140  [$00:2140]   A:0380
Here it gets muted when entering a cave with 80

Dungeon is 02 and whatever. You can cheat for the tracks with 002140xx with xx being the track number.

Make a trace with geiger and search for sta $2140 to find the place where to hook.

Pevkoss and I colaborated via mail and this project is finished as well

Third Quest: https://drive.google.com/open?id=0B68bmgtrAXQAZkd3WHNCbGlIeGc
Fourth Quest: https://drive.google.com/open?id=0B68bmgtrAXQAWElRS1lacHU1c3M

As soon Shirju finished a video, I will post it in the database.