So, it looks like an AVSession also needs to be created. I added the following code, and it now works on the device the same as in the simulator
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
BOOL ok;
NSError *setCategoryError = nil;
ok = [audioSession setCategory:AVAudioSessionCategoryPlayback
error:&setCategoryError];
if (!ok) {
NSLog(@"%s setCategoryError=%@", __PRETTY_FUNCTION__, setCategoryError);
}