There's a powered sub in konzert brand, the KS-12w model with power handling 300watts, in their web-site has no indicating if it's max. power or the minimum power, but I think it's maximum power or the peak power, just like the US audio brand(that I owned). The US audio is under license of Dai-ichi speaker and Yamaha electronics it's 12" driver and the model is US-512L-2, the power handling is 180watts with the peak power of 350 watts, frequency response 50Hz to 180Hz, 6 Ohms.(band-pass type sub-woofer)
*I use this sub-woofer for indoor use only.