It moves the speaker into the cone/dome category, but it is high efficiency so it's nice with your low power tube amps. This tweeter is a 4 ohm device, but with the cap and resistor, system impedance is still about 8 ohms until above 10kHz, where it only drops to about 6 ohms. Both the efficiency and the impedance curve of the loudspeaker is very nice for tubes and response is very good too. Something to think about.