I believe that is correct, as a general matter. But regardless of what an AVR is calling it, if the crossover is 40hz, then that is where it is crossed over. So Small at 40 or Large at 40 should not matter at all.
And in general, this advice about crossing over lower than 80hz makes perfect sense and cures my problem with the "traditional" put it on small and 80 and forget about it. The sub should work in the very lowest end. The higher the frequency, the more localization you get, and the more your image degrades as a result. If you mains work cleanly to 50, then cross at 60 (most have 12db (??) roll off so still getting some 50 and 40 hz material) and set the sub to pick up at 70hz (again rolling in to run full steam at 60).
The traditional arrangement was, I think, based on the fear many users had cheap and/or small speakers that could not actually get down to 60, or even 80hz, cleanly. Distortion in bass is less noticeable so they let the sub have it, as even cheap subs can make an 80hz sound, but a driver making 600hz sound and distorting on 60hz material will sound bad. That was a bad deal for people with good gear, and I was am surprised how many people crossed over great towers at 80hz because that was the default Dolby setting.
Glad to see it is improving. Now I need a new AVR so I can run my towers at small/large and cross at 40 or 50. Right now I use large as 80hz is my only option, but imaging in much better with the towers running full range (down to their internal crossover point).
