Drubin.Tou are correct that the original designs were designed by C.H.and that the design goals have changed to give consumers more bass.However when you port a system you are enhancing bass volume (as in loudness)NOT bass accuracy.If you are or were privy to the extensive scientific documentation supplied with these earlier designs(the original owners manuals,which were extensive books)it would be obvious that a great deal of research had gone into outlining to the,then,Avalon owners that the designer felt a sealed enclosure was far more accurate than a ported design.Comparisons were made with virtually all types of low freq. systems (port,trans.line,servo etc.)proof was offered up in the way of graphs and measurements that clearly showed the superiority of a sealed box.I'm not trying to be defensive or antagonistic I'm merely claiming from a practical standard that Avalon felt they could sell more product by encorporating the crossover into a more manageable enclosure and decided to port it in order to make it more room friendly(I don't blame them,but they are LESS ACCURATE at reproducing bass and midbass).Take a look at the comments in TAS regarding the DIAMOND's mid bass quality.Better yet listen to a really well designed sealed enclosure(of which there are to few designs).I really am sorry if I sound Preachy,but I'm amazed at the number of pricey products from companies like Kharma,JM Labs,Wilson etc.that have loads of bass that the average audiophile(not music lover)can't wait to throw their bucks at.I have a friend,a retired reviewer,who has a 22 year old set of Infinity RS-1's(updated crossover) that makes a mockery of the vast majority of rediculously overpriced stuff out there.I don't mean to include Avalon in this category but having heard almost all of their newer stuff as well as the older "classic" stuff it just leaves me scratching my head at what the audio consumer considers acceptable(at these prices).