I have a Clarion APA450 amp. I am running a pair of Infinity 4" reference in the front and 6x9 blaupunkts in the rear. I was thinking of going to an 8" sub like the RF Punch Stage1 P18S4 or Polk Audio db Series db804. My amp is 400watts, 50 per/channel. If I bridge the rear channel that should be 100watt for a sub. I dont care about booming bass that sets car alarms off or anyting, just good sounding bass. The 6x9's do pretty good, just wondered if my amp could run a sub for the future. Thanks in advanced for any info.....also...I havce the amp set to LP and bass boost for the 6x9's...would I do the same for a sub?