Avia, VE, receiver test tones and sine waves will all give different results. Which is "correct" ? None of them. All of them. Perfect subwoofer calibration is not only arbitrary but not even possible (in an untreated room). Try this- get the level just right with whatever noise reference source. Then move the meter 6 feet in any direction. Level will change by as much as 10 dB. So the calibration is only valid for one noise set at one point in space. Besides, even if it was possible to get it perfectly calibrated- what have you acomplished ? You will then hear the amount of deep bass that the engineer mixing the track intended. So what- thats just a person with an opinion- no more or less valid than your taste in level of deep bass for the soundtrack. The answer is to just let the sub trim float and adjust to taste, movie to movie. If it sounds weak, crank it up a few dB. If its annoyingly over bassy, dial it down. Treat it like the main volume- set where you like how it sounds- movie to movie. Why enforce the sountrack mixer's taste on yourself if you like it more or less bassy ? Note, the above remarks do not apply to music playback in a treated room and/or equalized subwoofer. Then a flat FR does matter.