iMac- external subwoofer and built in speakers

I just got my first Mac and was wondering if there was anyway to use a subwoofer through the headphone output while still keeping the internal speakers playing. That way I can have the treble and mids playing on internal while having the bass go through the sub. Thanks

Not that I know of. You might be able to keep the internal speakers going at the same time using the Sub Woofer system by attaching an external audio adapter. This from Griffin might work for you. (If you can find one for sale.)

Frankly, if you want to go that rout you're better off hooking your Mac up to a Stereo receiver and then messing with real speakers.

I just didn't know if there was a way to use MIDI. I don't really know what it is but some research online led me to that utility. Don't know if that can do it or not

You could try the TwelveSouth BassJump.

Twelve south bass jump is the ticket.