Just got an issue report (https://code.google.com/p/libgdx/issues/detail?id=1374) stating that stereo audio files aren't played back correctly, ie they sound more mono. After some digging, it turns out that this is an issue in OpenAL (http://opensource.creative.com/pipermail/openal/2012-December/012621.html) itself. This should be fixed in OpenAL Soft 1.15, could you folks update to that?
Updated nightly builds to latest version of OpenAL-Soft 1.15.1 43b406ad9bb32ebde78d26255a2a4f4a09a29926
Also noticed the OS X builds of OpenAL-Soft were x86_64 only (oops), so was probably falling back to the system OpenAL on non 64bit systems, anyway fixed now so that its an universal binary that runs on both i386 and x86_64.