Mac & Mpc

Convert mpc files:

Mpc2aiff

mpc2aiff is a front-end interface for the command-line utility mppdec (by Frank Klemm), which will decode mpc files (musepack's mpeg plus; other supported extensions are "mpp" or "mp+") to aif format.
If you usually surf the web and share music, then you should know what is this format (or at least the mac-unplayable ".mpc" extension), a high quality compression algorithm based on MPEG.
mpc2aiff will convert these files to ".aif", suitable to burn to a CD or whatever other utility you give them (such as convert them to mp3).
Link

Play Mpc files:

Cog
free open source audio player for OS X


Currently it supports the following formats:

• Ogg Vorbis
• Mp3
• Flac
• Musepack
• Monkeys Audio
• Shorten
• Wavpack
• AAC
• Apple Lossless
• Wave/AIFF

Link