Spiker, thanks for the info. I am familiar with the rudiments of loudspeaker design, having toyed at one point with the idea of building some speakers.

I am also aware that the folks at THX and Dolby have found thru their testing that bass frequencies under 80Hz are not localizable, hence the 80Hz crossover in most a/v and all THX certified processors. But all of that is more reason to use sealed speakers with F3 of 80Hz. Yet I get the impression that most people do not. I'm very curious to know why.