You know there is one thing that a lot of people overlook/ or do not realize. Running full range to all the speakers requires your amp to work a lot harder then if you have the speakers set to small and let the amp in the sub do the work. On lower end amps the results can be very dramitic as the unit will run much cooler and cleaner without running out of headroom as quickly as it will with the speakers set to large. Low frequencies require a lot more power to produce then do the mid and high range frequencies.
