Not to butt in (), but if you're like me you'll research this a bit, starting with the power rating of your speakers. I know that more power often improves sound in that the amp has a better grip on the speaker. Things get tighter, cleaner, more controlled. And while the amps were of different manufacturers, going to 500W from 200W yielded improvements for me. Looking at it on the surface, going lower (which a sub will let you do) doesn't mean the quality of that bass will be better necessarily; if it's a sufficiently powered sub, perhaps. I'm no expert and have never owned a subwoofer, so take this for what it's worth.