Power Switch: Changes the power settings of the subwoofer. There are 3 positions. Fully downward, "Off", will have the subwoofer completely powered off at all times. The middle position, "Auto", will have the subwoofer automatically power on after receiving signal. The fully upward position, "On", will have the subwoofer completely powered on at all times.
Phase: Controls the polarity of the frequencies outputted. If you have 2 subwoofers in your room/theater that are facing each other, put one at 0 degrees and the other at 180 degrees so that they don't cancel each other's frequencies out.
Level/Gain: Essentially, just a volume knob. You can control the subwoofer's volume directly here. Or, you can simply set the knob to about 60-75% (about 2 or 3 o'clock) and then control the subwoofer volume within your receiver or pre-amp settings.
Low Pass: This controls the crossover point. The crossover is the frequency point where the subwoofer will take over from the other speakers in your system. We always recommend starting with the crossover (Low Pass knob) set to 80Hz, but crossover points can be a personal preference. Try setting it to different places and see what sounds best to you. If you are controlling the crossover point within your receiver or pre-amp, you will turn this knob all the way to the right. Most of our powered subwoofers will have this point labeled as "LFE".
RCA Inputs (L/LFE & R): This is where you will plug in your single RCA or subwoofer cable. Since subwoofers only output a mono signal, you will only need to plug into one of the RCA jacks on the back of the subwoofer. We recommend plugging it into the dedicated LFE channel, which is the white RCA jack labeled with L/LFE.
For more information on plugging into a single RCA jack on your subwoofer, please see our article - Is a "Y" Splitter Needed to Hook Up My Subwoofer?