Phil,
Your friend, Brian Miller, asked me to add a few comments here in hopes that I could shed some light on the Innersound amp.
As an Innersound dealer, I have had the opportunity to compare the ESL with a number of very fine ampliefiers, using ESL, ribbon and dynamic speakers. Here is some perspective:
One of my customers has a pair of Martin Logan Prodigies. Comparing his McIntosh MC-2000 tube amp, the Innersound amp sounded much more open, dynamic, lively, controlled and detailed in the low end and extended in the high end. The MC-2000 did have a warmth in the midrange and richer harmonics too. Overall though, the Innersound was much more transparent, neutral and faithful to the music.
We also compared his Linn Klimax monoblocks and were shocked to discover how threadbare and harsh it sounded compared to the Innersound. The Innersound was much more relaxed, yet dynamic sounding with a warmer, more musical presentatiion. My customer bought the Innersound that very evening and has lived very happily with it for the last year. For what it's worth, both the McIntosh and Linn amplifies cost $15,000 vs $3000 for the Innersound amp.
Another customer contacted me to audition the ESL amp. He is a die hard ESL speaker devotee from way back and was in search of a new amp to drive his Acoustats. He came over to my place with his Wadia transport and DAC and connecting them directly to the ESL amp, driving a pair of Innersound hybrid ESLs. He was impressed enough to request an in-home audition of the amp.
We got together a few days later for the audition. I first listened to his system using his current amplifier, an older Bel Canto single ended, class A tube amp delivering approximately 50 wpc. He had listened to many other amplifiers over the years, both tube and solid state and felt that overall, the Bel Canto worked best in his system. While the amp sounded very musical, it sounded closed in, compressed, rolled off in the high end and lacked control and detail in the lows. The Innersound improved upon all of these categories to a huge degree but was lacking in harmonics, soundstage depth, image specificity, and overall refinement.
After listening for about an hour, I finally told him that I brought another amplifier with me that I felt bested the Innersound and happened to be $1000 less expensive.
That amplifier was the Electrocompaniet AW220. After listening to AW220 for literally 30 seconds, he turned to me and said with a pleasant surprise "You are absolutely right. This a beautiful sounding amplifier. I've never heard my Acoustats sound so good." Over the next couple of hours we noted the improvements over the Innersound in harmonic complexity, soundstage depth, image specificity, inner detail, micro dynamics, midrange pulpibility, low end slam, fullness and control and overall musicality. Keep in mind that we were comparing the 300 wpc Innersound to a 75 wpc Electrocompaniet. Very interesting. Needless to say, he bought the amp and both he and his friend are now considering buying three more, to be used as monoblocks in each of their systems.
The AW220 is a fully balanced (right down to its dual power supply transformers) high current design, biased into high class AB. Used as a stereo amplifier, it puts out a very strong 75 wpc into 8 ohms, 125 wpc in 4 and 160 wpc into 2. As a monoblock, it deliver 220 watts into 8 and 350 watts in 4 ohms.
One last testimonial. A certain manufacturer of hybrid ribbon speakers recently replaced his $7500 reference Plinius SA-250 amp with a pair of Electrocompaniet AW220 and hasn't looked back. The best part is that the AW220 cost only $4000 per pair.
Don't get me wrong, the Innersound ESL amp is one of the very best amplifiers available for driving panel speakers but the AW220 has bested it with every pair speakers I have tried thus far, including Innersound's Eros and Isis hybrid ESLs.
Hope this helps.
