The Absolute Sound posts a video about a new product development from Magnepan, but...

I use four subs to support my 20.1s. Two Kinergetics towers with five 10” Seas in individual enclosures powered by a Pass X-250. I also have two 16” sealed SVS SB-16 Ultras to fix the room modes. They integrate seamlessly and I vertically bi-amp my Maggies with a Danville crossover (what an upgrade from the MiniDSP) with all 8 channels containing 12 biquads each generated by REW and MSO. (I think it would be difficult to get the subs to integrate properly without these tools). A story to speak to the integration, we had company this last weekend who became one of three people brought to uncontrollable tears listening to their favorite piece of music because it transported them to the event. I am happy to say that no system I heard at AXPONA was better. The Danville room used a pair of Maggies as their demo for their crossover and the improvement it had very effectively. I did get a chance to listen to Dr. Edward Choueiri speak downstairs and listened his demo upstairs of BACCH 3D and it was astonishing how the walls disappeared. My wife, dad, and I were blown away. I built my system based on his principles I read about over 20 years ago. It was a real treat. 

I agree that ditching the factory passive crossover was a huge improvement and I also bought Grant’s stands for my Maggie’s and the sound improved dramatically. I designed and had him build matching stands for my Kinergetics as well for both looks and stability. At AXPONA I was impressed with the Magico A5 speakers so much so I did research on the company that night and was very impressed that Alon Wolf, who I met at the show, stated in an interview that they support even their top speakers with multiple subwoofers to tame the room and the reviewer asked him if that was the easiest way to improve a stereo system and he said absolutely. I agree wholeheartedly. 
 

Thanks,

Steve 

Most of the Acoustat panel speakers can be modified to use the Acoustat servo amps. Roger Modjeski did some mods to my servo amps, but unfortunately he passed away before we could implement the tube input stage. I modded my Model 2s with help from Roger where we implemented his mod to increase treble dispersion to greatly widen the sweet spot. The challenge with the Model 2s is when you remove the interfaces to connect the servo amps the speaker is challenged to stay upright. Rob from Magna Risers made me custom feet similar to what he makes for Magnepan speakers and they work just great. I assume they work great on Maggies as well.

@clio09: I remember that Roger often extolled the virtues of the Acoustst panels themselves, but considered the transformers absolute junk. Do you have the only pair of Model 2’s he worked on?

By the way ESL fans, Roger advised me to cross-over my Quad 57’s (originals) to subs at 100Hz using 4th-order filters (24dB/octave), as he found the bass panels to be unacceptable below that frequency. He deplored resonances, whether electronic or acoustic.

@bdp24 I believe I do have the only Model 2s that are modded by Roger. My experience with Acoustat came from the fact that Roger had a pair of Xs. He used (actually butchered) the cabinet so that he could test his own ESL panel and power supply. I was using that pair of speakers in my system when until I spotted the Model 2s for sale locally. At which point Roger told me to grab them and we went to work on those. Sadly I will need to sell them and the servo amps, as well as two pairs of my 57s (including Rogers own pair that I had Sheldon Stokes restore). Other than running RAM Tubes I'm retired now and I just have too much stuff. I also do still have Roger's own ESLs with his direct drive amps which I will keep.

Crossing over ESLs at 80 to 100 Hz depending on the speaker makes a lot of sense. I wish more people would try it out. I think one of the more interesting developments in ESLs these days is David Janzen's reworking of the KLH 9 which his father originally designed. If I could only have a pair of those.

@clio09: The KLH 9, another ESL I’ve never heard. I think that model never made it to the West Coast (in 1972 the leading high end shops were in the North, East, and South. Guys like Paul Heath in Philadelphia.).

When I discovered J. Gordon Holt and his Stereophile Magazine in 1972, he had double-KLH 9’s as one of four loudspeakers comprising his list of Class A Recommended Components. The others were the new Magneplanar Tympani T-I (in it’s revised incarnation, which improved the T-I’s high frequency extension), the Infinity Servo-Static 1 (which I did manage to hear, but at $2,000/pair---in 1972 that was lot of dough---were out of reach for me), and the Hartley Concert-Master. He had the Quad ESL in Class B.

Another ESL I was interested in was the Dayton-Wright, made in Canada. I went up to a new hi-end shop in Berkeley to give them a hearing, the shop owned and operated by David Fletcher, who later gaining notoriety as the designer of the Sumiko "The Arm" and the SOTA turntable. David struck me as an extremely intelligent fella, and when I couldn’t hear the Dayton-Wright (I don’t recall why he couldn’t demo the pair he had), I asked David about the Tympani’s (which were at the top of my list to audition). He was unusually candid when he said "I’m pushing the Dayton-Wrights." 😉