I am nowhere near a -15 dB sub adjustment before playing with trim.

Sub is on and playing the music prior to (and during) attempts at making adjustments. I wasn't sure at first, so I turned up the master volume and am 100% sure that the sub is operational with 2-ch music.

If I INCREASE the sub trim using the remote, I get zero increase in sub output (to +15 dB -- no change by ear or feel of the driver). If I decrease the sub trim with the remote (to -11 dB), I get no change (by ear or feel). At -12 I get a huge increase, as we all know.

I'm not saying that I know the answer, but I'm pretty sure that these are NOT the problem:

Sub is off
Sub is unplugged
Sub is broken
Sub auto-on circuitry does not work
Sub is not connected to 990
Sub volume is all the way down
Crossover is upside-down
Phase lock is cracked
Power is out
Power cable is broken
RCA cable is broken
etc., etc., etc.

I will double-check everything tonight.

Thanks!

-- Otto