I want to buy a subwoofer for improvement of HiFi listening. I am the owner of a pair of Canton RCL speakers and although bass output is acceptable I'd like to improve. Is there a thumb rule for choosing power output of the sub related to the (nominal) power output of the stereo speakers? My guts tell me the power output of the sub should match that of the speakers. But is this correct? The nominal power output of the Cantons is 200W. I'm aiming at a REL sub. Which sub (power output) will provide best performance with my speakers in a HiFi setup?