Audio files on Android installed on a Mac in Virtual Box

Hi

(Not sure if this should be here or in the Audio Board)

I have Android running in Virtual Box on a Mac. It mostly does what I need it to do, but it doesn't play audio files (mp3). When I try to play the files through an app that I've developed, it sometimes crashes the app, and other times does nothing. When I try to play the audio files through the Android media player, the visual on-screen show it playing, but there is no sound (yes, the speakers are on).

I can't easily download other apps, because Google Play doesn't recognise it as a device, and won't let me download apps, so I can't easily test other players (I can, though, download a raw .apk file and install it manually).

Any suggestions welcome.

Thanks