N5DUX

I got some ProMedia 2.1 speakers a few months ago. I'm wondering if anyone has the pinout for the DB9 connector on the sub. I've seen others post the DIN pinout, but since the connector is now a DB9, I'd like to find the wiring order for it. If nobody has it readily available, how would I go about testing/measuring each pin? (I have a voltmeter to assist in doing that.)