Sorry if this has been answered before but I am not able to find the answer to my particular problem.

I have AudioBox 1818 USB, MacBook Pro with OSX 10.9.5, Studio One 2.0.

1. I have a TEAC A-3340S outputs connected to inputs 3, 4, 5 and 6 on Audiobox. A-3340S is playing material we recorded with a previous band.
2. I see audio on all the input meters and the main out meters in Studio One.
3. I have Audo Input set to the Audiobox and Output set to headphones on the MacBook Pro.
4. I can hear audio in the headphones if I play a youtube video.
5. I see the bottom two LEDs on the Audiobox output meter flashing

But I have NO audio in the headphones.

I tried plugging the headphones into the Phones jack on the Audiobox and still no audio.
I do not have the record/playback knob on my Audiobox that I've seen in some posts with answers about no audio.

Any suggestions?

Thanks,
Don