Exclusive access will definitely produce this symptom. After turning it off, you'll probably need to shut MC down and restart it. Then make sure your setting stayed unset.
I use MC all the time without exclusive access and my other sound programs can talk to my sound devices just fine, even with MC running. I'm using OS X 10.9.5.
Brian.
I'm using OS X 10.11.5. I've been restarting my Mac every day. That ought to do it
But I found the problem, although I've got no solution.
I'm running MC on two Macs. The first one has but one sound output option, headphones. On that Mac, other sound programs work even with MC running, just as it's supposed to be.
On my main Mac, I've connected a DAC via USB (NAD M12). In the sound control panel I've chosen that device as default output. I've got two other options, which I have no reason to select (see attached screenshot). In MC of course, I've chosen the NAD as output device as well.
Now, when launching MC I've noticed that the control panel setting gets changed to "Samsung HDMI". When quitting MC, it get's changed back. That's why I hear no sound from other programs, unless I listen to the HDMI output. Needless to say, I'm not interested in constantly switching forth and back while using different programs. I want to use my USB DAC for all sound output.
To put it a different way, MC doesn't prevent other programs from outputting sound, but will not allow output to the same device it is using itself. This kind of amounts to the same "exclusive access" setting, doesn't it?
I see no reason for MC to change the sound control panel setup, even temporarily.