I'm sorry to but in, but as far as I know the ATC response of +/- 1 - 2 db doesn't call for extensive eq IMO as it's only usually used before the LF rolloff and again crossed over to the tweeter long before it goes into resonance mode. ATC's active amplification packs ONLY work with the 16 Ohm drivers they use in their own amps.

All this reading on this thread (and the now deleted one on PFM) got me thinking. Why do ATC cross over from the bass unit so low in frequency? Maybe this has already been answered (apologies if so) but ATC make huge reference to consistant dispersion. Am I right in suggesting that crossing over as low as the dome will go maintains mid dispersion consistancy.

ATC did design and make a prototype of a larger dome, but couldn't find a tweeter for it. Perhaps they should try a smaller one which goes up higher?