How To: Set your Amplifier Gain - SSA Car Audio Forum
As for your Sub Sonic filter, what kind of enclosure do you have? If ported, a lot of people recommend setting it a little bit under tuning... for instance, if your enclosure is tuned to 35hz then set the SSF @ 30hz. If sealed, most people just leave it off, or turned to the lowest setting. I leave mine off period, because music I play tends to dip rather low. As for bass knobs... I usually just leave them unhooked. Phase is referring to your + and -.... sometimes people reverse the polarity to help the subs response if it seems slightly behind the rest of the music... some headunits can control this as well. It's sometimes used as a bootleg time-alignment. Low pass is your low-pass filter... basically whatever you set that at, frequencies lower than that will be passed on the the subwoofer. I usually set mine around 60hz, but some people like their subs to play higher than that.
