This Kenwood 9105D 1800w monoblock amplifier is a bass-only amplifier designed to drive subsonic frequencies to your subwoofer. Assuming you already have a stereo amplifier for your midrange speakers and tweeters, the monoblock comes in as a complementary amplifier to fill up the acoustic gap and punch in low frequencies to your subwoofer.
Though it is designed to go into your car the excellent low pass filter and class D design circuit have made quite several users customize it for home use