Setting the B1800D-PRO will be subject to music genre played as well as room type/size, etc. but here are a few guidelines you can use:
1.) Start by setting the controls. Turn the LEVEL knob full counter-clockwise, HIGH CUT knob full clockwise, BOOST FREQUENCY knob centered, BOOST switch set to OFF, and PHASE set to the NORM position.
2.) For the LEVEL knob, start with it set full counter-clockwise, then adjust to desired volume level. If the LIMIT LED flashes continuously, turn the LEVEL knob back down until the LIMIT LED flashes only occasionally.
3.) Slowly rotate the HIGH CUT knob counter-clockwise until you find the best sound balance between your B1800D and the other speakers.
4.) Move the BOOST switch to the ON position. Rotate the BOOST FREQUENCY knob until you find a suitable low end frequency.
5.) To compensate for possible phase cancellation between the subwoofer and other speakers in your system, move the PHASE switch from the NORM position to the REV position. Keep the setting which delivers the best-sounding result.