id have to re teach myself alot on this, but you want to set it so that its as close to no added extra levels at all. my bass boost is at zero. gain is at zero and lp filter is set to which ever direction allows the most bass to come through. this is of course with me having full range speakers and having the head unit set as flat as possible.
see when an album is recorded they set their guitars and everything else to sound exactly like they want...such as amps and eq on that instrument. BUT when it is recorded they record everything flat so it doesnt add or take away from their amp settings. soooo you want your system to be set flat as well so that it doesnt add or take away from what the artist recorded.
as i said, i dont remember to much.