what should i have my filter set to on my amps for speakers one is a alpine flex mrp-t406 and a pioneer GM3100T, The alpine has three options for the filter 0FF, HP , AND LP (IT SAYS 80HZ UNDER THE OPTIONS) and this is what is one the pionner Selectable LPF (80Hz, -12dB/Oct.) what should they be at...? they are for 6.9s(gm3100t) and 6.25's(alpine)...thanx in advance