In order to shrink my HT footprint I recently replaced a full size VP 180 with the same model in an "on-wall" version previously commenting how close a match it was to the original so I decided to carry it one step further ordering a pair of "on-wall" M5s to replace my 10 yr old V2 M80 floor standers. In addition to being the only speaker, regardless of size, in the on-wall line-up to have the HP woofer as standard equipment and, I gather to accomodate the bigger magnet, the M5 being three-quarters of an inch deeper(4 and three quarter inches). compared to 4 inches deep, none of the others can even offer the HP speaker as an option.

I was just curious as to this design/model choice and IF it is a case of the HP version requiring the "box" to best function, without giving away any trade secrets, perhaps Ian can chime in and why the decision on only the M5 and why does it work in the "on-wall" version where there is obviously virtually no air movement whatsoever?