Why is there no sound output from Quicktime player?

I can’t get Quicktime player to give me any sound output, for example if I try to play a WAV file, and MP3 or audio from a Quicktime movie. The files open OK and the movie plays but there is no sound.

If I open the WAV, MP3 and movie file in VLC player, the sound comes out fine.

This problem occurs with both Quicktime player 7 and 10.

I’m on Mavericks 10.9.5

My audio interface is an Apogee Symphony system that otherwise works fine.

Thanks for any ideas