Do 1st Order XO's produce a smaller

Calantus... I concurr with your assessment of the MBL's. They through a huge stage act to be sure,but another design that requires giant sized amplification to energize. Now those Duevels are really intriuging... exotic wood options...with a real world sensitivty and impedence load. Do you know where one might audition these in North America?

Ecclectique - regarding the Duevel's and Tannoy's. With respect to the Duevel's I've read some reviews on the Bella Luna and they sound very promising, with some inherent limitations. You can probably get some dealer info. from this site:
http://www.cd-konzert.de/loudspeaker.htm

Another interesting speaker design concept worth noting is the Oskar Heil A.V.T. (Air Velocity Transformer). Oskar Heil Speakers has recently introduced a new model called the Kithara ($4,900). The A.V.T. uses a lightweight diaphragm, folded into a number of accordion-like pleats to which aluminium foil strips are bonded. The Diaphragm is mounted in an intense magnetic field and a music signal is applied to the aluminum strips. This causes the pleats to alternately expand and contract in a bellows-like manner in conformance with the music signal forcing air out of the pleats and sucking in on the other side, the air movement is 5 times bigger than the movement of the membrane, therefore also the velocity must be 5 times bigger. The benefit of this transducer design is better differentiate sounds.

Tannoys! I've worked in the multimedia industry for over 14 years and spent many hours in professional editing suites in NYC, Los Angeles and Atlanta, so you know I've heard a lot of Tannoy professional monitors. The Tannoy monitors I've heard are absolutely fantastic, practically an industry standard in the '90's. However, I didn't think their floorstanding speakers were able capture the same magic, especially when I listened to them next to Vandersteen 5's and Martin Logan's. I thought my Hales T-5's were far superior to any of the Tannoy's I listened to.

You're right this is a very interesting subject. Perhaps the ultimate speaker is a hybrid that includes an active sub and mid-range and a 360 degree tweeter design.

Someone mentioned 6moons reviewing the GMA's soon, but they already have a review of another 1st order design, the Gallo Reference III that is really quite a gushing review, even considering the normal gushy nature of speaker reviews. I guess it is time coherent too based on the driver placement but I could be wrong.
The CDT design sounds like it would somewhat address the narrow sweet spot issue. I plan to go listen to these speakers sometime this week, I'll let you know what I think.

Dawgbyte. I do remember the original ESS Amt-1 from the mid 70's. I actually owned a pair for a brief period [3 or 4 months] and traded them in for the Dalquist DQ-10. I would hazard to guess the modern versions would surely be a substantial improvement in order to compete with many of todays high end speakers. Regarding the Tannoys: My previous reference to them was based strictly on the earlier Alnico based 15 inch speakers[pre tulip waveguide versions] and not the studio monitors per say.I too; have worked with the pro series Tannoy studio monitors, in both the studio and live gigs... both indoor and outdoors: and to be candid here... they just do not compare in any which way whatsoever. Ever heard a Tannoy Westminsters in a large room? No offence here:as the Vandy 5 is indeed a very impressive speaker,but sorry.... the Vandy 5's were not even close in my room. Perhaps my studio is a little on the large size for them at 35ft x 27ft with 16.5ft ceilings.That said, I also much preferred the Proac response 4 to the Vandy 5 in the same room as well. The Vandy certainly had the better bass foundation, however the proac was closer at recreating the illusion of a live event in the studio. It was also preferred in a smaller adjascent room as well. In a typical listening room found in the average home, I believe there are many speaker choices. The room size and the rooms acoustics would surely dictate ones choice. Small speakers for small rooms and so on. Any veteran audiofile should be well aware of ones room volume and choose the appropriate speaker for his or her room. I have heard far to many systems whereby the speakers were far to large for the room and vis-versa. In my earlier thread I mentioned the Morrison speaker,It may be worth checking it out for those intrigued by omni directional point source speakers.His web page is donmorrisonaudio.com....I should point out that I have no affiliation in any way with this company, however..... To be blunt and honest here....to my ears, they are impressive music makers indeed!

Dawgbyte, the Adam Audio speakers use the Heil principle, not only for the tweeter but also for the midrange (on some models). Check them out: http://www.adam-audio.de/

True, the MBLs need big amps, and they also have an inherent weakness: Some kind of sharpness in the upper mids, which really stands out at higher volumes. I wonder whether a big tube amp might smooth it out...e.g a VTL Wotan.

Duevels are imported by 'High End Audio' in Connecticut: http://www.highendaudio.com/index2.htm