This 4 way,4ohm speaker has a sensitivity of 93.5db. Source componets are a Jadis DA-5 tube amp at 40 RMS, Jadis DPL-2 preamp and a Jadis JD-3 CD player. This wonderful speaker has the same crossover and coaxial midrange and tweeter of the $82,000 flagship Atlantis. I have not had much time with this system, although I can tell you that with the associated equipment I have not begun to hear what is capable with this speaker. Don't get me wrong, except at extremely high volumes, which compresses the treble soundstage a little, the music is awesomely dynamic and full. The piano is in the room, vocals have no distortion at any level, bass is full and clear, it is only limited by the room and the 40 watts driving it. There is plenty of power and at a sensitivity of 93db you can hardly turn up the preamp past 10'oclock with blowing your ears out. On the back of the speakers are 4 sets of inputs to drive each driver with a seperate amplifier, and with one amplifier driving the speaker each input has a different effect to the speaker because of the different impedance inputs. I have been a professional drummer and my wife has sung professionaly and we can attest that the purity of the sound stage,dynamics,and the pacing of the music is truly amazing and can only be improved by upgrading the Jadis equipment, belive me when this is done you are hearing things on this speaker that you did not hear before, it is unreal. My wife and I have waited for 15 years for this and we are so happy with the system. I am a firm vinyl person, as good as this sounds with cd I cannot wait to get my turntable out of storage. You too can experience this in your home, go to www.northstardirect.com for a home trial. TUBES AND VINYL ALL THE WAY. mark duckett