What about size = quality, because that is one reason why cost goes up in a line as well. Hence, does the world's largest speaker automatically sound better than anything smaller?

If you price out the M50s which are more expensive than the M22s, i think the M22s have a better sound quality. You could qualify that sound by a more linear frequency response if so inclined.
I certainly don't think you can literally line up every Axiom speaker from lowest price to highest and then qualify how each speaker is somehow better with every price jump.

I've never heard the M50's, so you could be right at that point. But don't see why anyone would want the M50's if the M22's sound better.

Was talking about the same speaker lines within the same company, so if it's the worlds biggest box, you'd have to compare it to the same companie's smaller and probably cheaper box. So the bigger and more pricier one would probably sound better.