How come the audio is improved (less muffled?) And what is happening to it exactly?
Is there like a broad application that can be snapped on to other GBA titles to do the same thing?
All I know is that the problem exists because the GBA was doing the heavy lifting through its CPU.
I dimly recall that there are various GBA hardware mods available to address the audio quality. I don't know much about them, though.
Google also suggests https://forums.nesdev.org/viewtopic.php?t=19688 and https://forums.nesdev.org/viewtopic.php?t=6408 , but I don't know if that addresses whatever might have been done to the DS and Wii ports. Do you observe similar changes in standard GBA emulators?
That does sound good. Im trying to see if there is a way to improve the audio through a machine like a MisTer. I thought itd require a per game mod but the core may just need a fork.