This was going quite a while back, if I recall correctly; the AG's were actually the Trio Classico not the Omega's as I had thought. The Trio Classico has that curved bar, where the horn tweeter can be adjusted by slope along this curve. Quite a tifty design concept but not found in the Trio's latest version though.
Either way, it presented very very high efficiency ratings, I think it was in the range of 120dB and above. With a very benign load of 16 Ohms, such high efficiency designs will amplify every tiny little detail. Going from the source signal along the chain, upto the speakers terminals, everything!
At the time, his gear was the massive Melos 400w Triode monoblocks, way overkill for a horn system of this nature. The preamp was Audio Note, I forget the exact model but was top of the line, and digital playback systems from Copland. All the cables were also Audio Note, which was very good, top quality stuff. This was basically the same gear that was used to drive his former Maggie's, Infinity's and later on Genesis speakers. So for those types of speakers, this combination of gear was excellent! In fact, outstanding!
Since the Audio Note preamp did generate a certain amount of hiss, it wasn't that noticeable from the listening position, so no big deal. Also the Copland CD player generated internal noise, a very slight hum whiles the motors were spinning. According to Copland this is normal and once tunes start playing, no big deal either.
Only when all those speakers were changed over to the AG's, holy hector! Those big Melos amps blew the roof off! It was like a live performance, I mean it really was. That's probably the first time I've ever heard a playback system capable of reproducing the actual event. Then of course, comes the recording, and all the flaws of bad or poor recordings came through like looking straight into a prism, you could see right through the music!
After the Melos amps were sold off, I think we tried 6 different amplifiers: Cary, Jadis, Quads, Golden Audio, CJ and Kondo Audio Note. All of them had different flavours and different power levels but it was the amplifiers with the least power ratings that matched better, mainly due to seriously amplified hiss. He kept the K-AN amps, which were just 8w SET monoblocks.
With this particular combination, the Kondo amps were able to "Tame" the Trio's, such that on soft to quiet passages, everything was more relaxing or least it had less "jump factor." Then, if things needed turning up with more dynamics and transient power, the Kondo's were upto the task. Those SET monoblocks driving the Trio's was one of the most effortless playback systems I've heard to date.
As with the case of the AN preamp, tubes were changed but obviously within spec, since tube rolling only offers different flavours, it really doesn't improve sound significantly. It only changes it. The other thing is, most tubes that are placed into a particular circuit design, have been developed in such a manner to obtain a custom sound. Hence, altering this sound is ok, as long as you're within spec but sometimes tube rolling can also have negative effects. Voltages and plate current are altered when tube rolling, so best to keep this fun activity to a minimum.
With the change of a few tubes on the AN preamp and Input gain tubes on the K-AN amps, all those unwanted pick up noises were minimised by a good margin. The music reproduced from the Copland rig was still enjoyable and the K-AN amps did an extraordinary job. However, there was still that hiss on very quiet passages, also the motors in the Copland were still audible from the listening position. So, the natural thing to do was increase the listening distance! And so we did, that was taken to 15ft. The initial room, where the other speakers were placed, was adequate for those types of systems. Definitely not for these massive AG's! The pics of the Trio Classico don't do justice at all, you have to see them in person, and then appreciate their beauty in awe, with flawless design and meticulous German engineering. It's at a very high level.
After the listening position was adjusted, we also added more soft furnishings around the Trio's base, plus sound absorbers behind the Trio's. This also helped with less noise floor, also AC mains were rewired, with CB's going directly to the mains board, which were dedicated lines. This was probably the most significant improvement of every other tweak. The dedicated AC lines for those Kondo amps contributed to the most quiet levels by far. So that gear and system remained for a number of years until just recently! He's just taken delivery of the Genesis Tributes (In honor of the late Arnie Nudell of Infinity Systems). These Tribute speakers will be driven by Dan D's Momentums. So that's a whole different thing.
Anyway, at the end of the day, nearly every type of tube associated gear will be amplified at high levels when driving very high sensitivity speakers, that's just physics. There was one type of SS amp though, that matched extremely well with the AG's, and that was the AG horn amplifier. It's really well designed and à beautiful piece of machinery. There's also an integrated version, which I've heard on the AG Duo XD's, it was fantastic! No tubes at all, just solid SS all the way.
This AG amp has no hiss at all. An outstanding performance with AG Horns. Below, I though I'd just add a pic of his Genesis Tributes, stunning! I'll get a chance to audition these coming Aug.
Cheers, RJ
