Is it not possible to upload .wav files for your songs? I want to have my users download .wav files not MP3s.. Soundgine trying to save CPU and storage by using MP3s.

Yea it's possible bro, maybe you aren't copy and pasting it properly? Try converting it into a .rar file first ??

dragdrop ya tagged mp3 into demo. Then into external url paste ya hosted link for zip packages like mediafire,rapidgator etc add price, art, etc done..its pretty simple