For your formats, you'd need ffmpeg (for ape), flac, and wavpack USE flags, plus whatever else applies to your system. I didn't see a specific USE flag for ffmpeg to enable ape support, so I'm not sure that the format isn't supported by default.
If nothing else, qmmp is very light because it only needs qt and not all of kde, so it wouldn't take so long to compile as amarok if you just want to try it.
