G'day mate, came across your post and the troubles you're having with your ESL's.
Just a quick note: There's no speaker in the world that operates on a fixed Ohm rating. Every manufacturer will present their specs as "nominal impedence." This basically means, that on average ratings, the speakers nominal load to start off with hovers around 8 Ohms for example. However, as the speaker plays tunes, this rating fluctuates with frequency range, and can vary as high as 22 Ohms and as low as 1 Ohm!
ESL's are notorious for a wide impedence swing, and this is the number one cause for many so called "capable" amplifiers to simply run out of puff! In fact, they go poof! Not all amps are even built the same standards, and some have very puney power supplies but the designers won't state that because if compared to real power amplifiers, their performance would look very embarrassing.
The typical impedence swing on ESL's are as high as 20 Ohms and drops to 1 Ohm in a blink of an eye! In some models, especially full range stats (Monolith, CLS, CLX) that impedence can drop to less than 1 Ohm, around 0.7 Ohms, which is pretty much a short circuit. And this is where the amplifier craps itself.
I'm not a fan of driving ESL's with AVR's and those types of fany featured gadgets... they really don't have the required power supplies to drive ESL's optimally. They're not designed to do so, rather they focus on HT and video applications, which don't require large power supplies to drive difficult loads. HT speakers are easy to drive and they present a benign load to the amplifier, thus the dynamic bursts and loud bangs in movie tracks... that's what AVR's are designed for.
However, this doesn't mean that the AVR makes you're using cannot drive your stats, they will but upto a certain limit. Hence, not optimally. The speakers that you used safely before the ESL's, where your AVR amps had no issues driving, are simply not ESL's! Their impedence swing must have been a far easier load to drive, hardly ever dropping below 4 Ohms. We're talking 2 Ohms or less when it comes to ESL's, the power amp must provide high current with highly stable voltage in order to control, drive and grip the ESL effectively. Only well designed power supplies are capable of doing this, regardless of Class A, AB or Class D operation in the Output stage.
I looked through each of your AVR model specs, they seem to be just about ok for low level tunes, audio and video, definitely NOT high level. By using these types of AVR amps at high levels, you will cause significant damage to the ESL stat panels, there's no doubt about that! But like I said, at very low to moderate levels, it will barely get by and you'll be able to hear tunes or whatever is playing but these types of amps are not suited to drive ESL's. They all have power ratings of only so many watts at 8 Ohm loads, they don't state their specs at 4 Ohms, 2 Ohms and less than that. For example take any well known power amplifier that's known to drive difficult loads: Parasound, Anthem, Bryston, Krell, Classe', Magtech, Plinius, Aragon, Mark Levinson, McIntosh, Moon- SimAudio, Pass Labs, Jeff Rowland, Dartzeel, Dan D's designs, CH Precision, Solution, Boulder, Gryphon, Burmester, Vitus and the list goes on... these are real amplifiers that will drive ESL's to top flight! They all have one major factor in common, and that is they all possess rock solid power supplies. They don't flinch under stress one bit and can handle impedence swings from high as 30 Ohms down to 0.5 Ohms, no issues at all. Such impedence swings in ESL's are referred to as "reactive loads" this is where the impedence reacts to the frequency range in opposite effect. So for example, when the ESL's reproduce a bass note, the impedence actually rises to over 22 Ohms then when the stats panel reproduce a high note with lots of treble and extended highs, that impedence drops to less than 1 Ohm!!! That's the scary part that will make most amps and AVR's run out the door.
Anyway, like I said, you can still use your AVR amps but with caution please. I would very highly recommend getting a dedicated power amp or multi-channel power amp since you're into HT... partnering that with the AVR's that you have will drive your ESL stats far more effectively. You'll never know until you've actually tried one out, then you'll realize just how weak those power supplies are in AVR's.
Note: Power supplies refer to: Mains Transformers, Output transformers, Capacitors, current buffer stages, voltage output devices and fast switching output devices to meet the demands of driving, and controlling difficult loads.
Hope that helps. Don't give up on your ML ESL's, and they do seem to have a problem. What you've done so far is the correct approach by contacting ML tech support/service, they'll definitely attend to it. Just be in touch with them and as our valuable members here have advised, just be patient. Once sorted out, you'll be happy as, and once you get the right type of amplifier, you'll be amazed at what those ESL's are really capable of.
Cheers, RJ
