In itself, the B&W 605 S2 is not a full-fledged active speaker, but a speaker with an integrated active subwoofer. According to the B&W brochure, the 605 is the unique answer to achieving a controlled bass extension without a separate subwoofer in a small space. (analogously)
The midrange and tweeters are conventionally controlled via an integrated amplifier, while the two woofers are controlled via the internal amplifier. The separate line-level LFE input can be controlled directly from the subwoofer output of an AV processor or amplifier.