Islandflyfisher,
This is probably too late for your purpose, but the color coding on the REL can be misleading. The BLACK wire from the speakon cable is NOT GROUND! The YELLOW wire is ground instead. Based on the manual, you should connect the red wire to the red terminal on the amp, the black on the black terminal (unbalanced on one side) and yellow to either terminal of the other speaker out terminal. And make sure that the gain is turned up as well. I have read and experienced myself that A LOT of people made the same mistake and couldn't get any sound out of the sub initially. Hope this helps.
This is probably too late for your purpose, but the color coding on the REL can be misleading. The BLACK wire from the speakon cable is NOT GROUND! The YELLOW wire is ground instead. Based on the manual, you should connect the red wire to the red terminal on the amp, the black on the black terminal (unbalanced on one side) and yellow to either terminal of the other speaker out terminal. And make sure that the gain is turned up as well. I have read and experienced myself that A LOT of people made the same mistake and couldn't get any sound out of the sub initially. Hope this helps.