Bower and Wilkins and its relationship with Classe and Rotel

"Oh, I didn’t know BMW made speakers"

funny! my dad said that when I showed him DM604S2 back then (I was driving a BMW also back then so i'm sure he had that auto brand in his mind).... ;-)

ct0517,
interesting read re. the B&W BAF.
I read the Ken Rockwell dissertation on the BAF & I believe there’s a typo in Fig 6 - 11 (that seems to be verified as one scrolls lower to the Rohde & Schwarz plots). The freq range (along x-axis) for Fig 6-11 have a "kHz" - i think that’s wrong. The "k" in the "kHz" needs to be removed i.e. the frequency range should be just "Hz". You look at the freq numbers as 50KHz, 100KHz & this is a bass alignment filter - it makes no sense at all. Human beings don’t hear beyond 20KHz + what kind of bass operates in the kilo Hertz range??
Anyway, once you get past this I see the BAF as a subsonic filter (which is also clearly mentioned in the B&W BAF manual) & by providing 6dB peaking in the BAF module B&W is able to extend the bass response of the speaker down to the deep bass region (20-40Hz). Yeah, I can relate to woofers flapping due to TT rumble - I’ve seen that before.
Many Japanese integrated & receiver amps from the 1970s, 1980s also had a subsonic filter switch (like my Yamaha CA-2010) which is a high-pass filter with a -3dB at 15Hz if I remember the contents of its manual correctly.
Yeah, I can see why the B&W Matrix speakers became "efficient" (altho I would not have used that term specifically) by addition of the BAF - the impedance in the deep bass region was increased to 6 Ohms (like the rest of the freq response) meaning that the power amp now can dump current into a large impedance to produce bass thereby taxing it less & like you said opening up the choices of power amps to drive such a large speaker. People who did not use this BAF had to find power amps that were capable of high current into lower impedances implying very expensive & heavier power amps.
The BAF is a gimmick for a speaker whose designer could not design it correctly in the 1st place & had to add a bass extension/alignment filter to fix a flawed initial design.
Ken Rockwell writes that the newer Nautilus speakers do not use this BAF (as it seems to have confused the public since many speakers were bought w/o the BAF + we all have seen several BAFs take a life of their own on eBay when they really have been tied to a particular B&W Matrix speaker model) & have bloated bass. He is very accurate in that statement - I 2nd it from all my listening experiences & my ownership. 

@bombaywalla, you are certainly entitled to your opinion. I have owned wide variety of Delta series amps in last 10 years and anyone out there will concur with me that their sound is no where near etched, screechy, bright, brittle or metallic.

Classe amps are one of the most neutral sounding amps and mate quite well with B&W speakers.

Ask the folks at famed Abbey Road studios :-)

it is true that we have very different experiences w/ Classe-B&W. Classe amps from the Dave Reich era (the ones that have DR in their model number) were some of the best & are still prized today. Once Dave Reich left (if I remember correctly he went to Theta Digital?), I believe that Classe amps become quite ho-hum for 2-channel. 
They seem to be going gangbusters for HT tho'....

The good folks at Abbey Road Studios - for monitoring the requirements are quite different vs. home audio. And, for studio monitoring the big B&W speakers makes a lot more sense.  

"Oh, I didn’t know BMW made speakers"

@ct0517, I know at least dozen folks who had the same response. Heck, I have guys come to my home and tried to grab the tubular tweeter thinking it's a microphone for karaoke :-)

I am hoping for mass awareness now that BestBuy start stocking 800 series speakers.

Happy Listening! 

Lalitk

no kidding. My dumb a-- brother in law showed up last month and tried to yank the tweeter housing off my new 803s!