Are you just loading the MP3 off an IDE HD from the internal IDE port? Maybe when you get the new MP3@64 try copying the MP3 to the RamDisk: and see if playing out of RAM makes any difference.
( I remember setting up my first 80meg HD back in '94 on my A1200 and had a hell of time with the Transfer Mask (I think) setting. Had to change it something like 0xfffffffff.... When the HD was first set up any single file that was over 128k got corrupted, HD was slow, etc.. That is obviously a totally difference simpton, but maybe could be something with the HD transfer??)
I was also unable to get my ethernet adapter to work through the credit card slot as i was told my mobo also needed a mod done because the port would not reset with the given software. I was unable to connect to my router so i ended up selling the ethernet card. Not all A1200's suffer from these above mentioned issues...
I had similar problems with my A1200 and PCMCIA ethernet card back in the day. There are two programs from Aminet that did the trick for me...
CardPatch.lha
CardReset.lha
As far as I know these basically replaced the need for the hardware patch the PCMCIA needed.
Good luck.
