[Malice]

Me being a complete half wit with the finer technical nuances in this thought room gain and modal gain were one and the same thing.

JohnM, your use of the word "resonance" perfectly describes what I appear to hear near the frequencies that Brucek has kindly chipped in with; with single test tones that I did over a year ago, the room seemed to take on a life of its own and nearly took off! People in the other part of the house were complaining about the loudness of it. TBH when I first set out to manually measure and EQ the sub, I tried to achieve a target level of 85db, but as I approached (with hindsight) the modal frequencies, particularly the one about 26Hz, the SPL meter was registering 115dB. No wonder there were complaints!