your right,however my on screen adjustment for lfe, initialy set at 0db adjustable to -20db, no posative db gain on rec.,anyway something else under lying is wrong, at first before i started fooling with my amp. trying to link, i have 4, 15" main's, alot of bass allready', but something i did, after a while,no bass in main's, and to activate lfe, you have to go on screen, and select both, main and sub. or the won't come on, still more so bass sound,not much subsonic, i assume the main line is feeding the lfe, or it won't work? god i hope i don't need a new amp.