Cork, when you say the v2 gave more of a concert hall sound vs. the v4 presenting more precise imaging, that is what I call improved spatial resolution. This is due to greater linearity in the family of frequency response curves from multiple improvements Axiom has made particularly in the last 7 years. This spatial resolution arises naturally when you produce a very linear speaker and then place two of them in a room and feed them stereo. Positioning within the room is quite important to get as much out of them as the design allows.
There also appears to be a movement in the speaker industry as of maybe 7 years ago that Axiom has embraced. This is the practice of defining the soundstage as being resolved behind rather than in front of the speakers. With well-recorded material, I hear the front of the soundstage behind the rear plane of v4. From there, it extends backwards. This is not the case with v2. V2 is forward. This is actually something Craig pointed out to me before I bought v4 and it was one of the features that made me upgrade my M80v2 to M5. The M5s were better in all respects.
A good question is how exactly does Axiom achieve this effect. One of the variables in the equation must be the midrange. They likely manipulate the family of curves to shape the midrange response and push the soundstage back without affecting fidelity. This is perhaps why you are hearing more mids with the v2.
Are you hearing a difference in depth of soundstage between the v2 and v4?
