Been messing around more, but it seems that no matter what I do MC on the Mac 'sees' everything in my library as 44.1/2 channel audio no matter what it actually is. Is that 'normal' and if not, any ideas why that is happening?
Edit: I take that back a little. My 'normal' use of MC on this machine is as a client to the master library. If I play the files from the local library, as opposed to using the master library then MC does see the files correctly. It is only seeing them as 44.1/2ch when running in client mode.
Library settings are at their defaults with audio set to convert when necessary - but it is not necessary to convert these files as they play back fine in native form. Set to 'do not convert', it is working correctly, but that should not be necessary should it?