Steve, I would be guessing more efficient translated into less heat generated at the same SPL -- not too many variables there, dome, suspension, coil and magnet -- ferrofluid also if it is present. Still interested in the compliance of the butyl rubber surrounds here. The ADS L-980's rubber is pretty compliant but maybe the AR design called for a longer throw. I doubt anyone is interested in testing the differences at this point beyond a simple A/B comparison. I seem to remember you had some issues with the baffle arrangement on these. Roger