No sound through speakers

I just made the switch from PC to mac. I'm an Ableton DJ and I only use a USB mixer in my setup along with an Echo AudioFire 4 audio interface.

When I used to play on my PC, I'd have it setup so that all my audio channels went out 1/2 and the cue was setup for 1/2 and master went out 3/4. Then I'd run the master audio back into my computer's sound card's line in and sound would come out of my speakers.

I have everything setup the same way on my iMac but I'm not getting any audio to come out of both my built in speakers and my external speakers that I have plugged in via the headphone jack on the iMac. Cueing works fine and I'm still getting audio through the headphones that are plugged into my audio interface. No sound otherwise.

I'm using the CoreAudio as my audio driver in the preferences.

Does anyone have any idea about a setting I should have on/off that I might not have set correctly or any other ideas? Kinda hard to play when I don't have anything coming out of my speakers :(

Thanks for the help!

keystone