Quad ESL-63 and low-powered amps; Sun Audio, Atma

Thanks to everyone for the responses. Sorry for my delay. It sounds unanimous about low powered amps even without any load below 50hz. My CJ MV-60 sounds pretty amazing so unless I can taste the magic of another circuit like single ended, or maybe a great tube like the 300b, maybe I should stick with the CJ. I.e. would an RM 200 really sound much better?

Also, as I look at amps, how can I tell from the circuit design, parts or measurements whether a particular amp can handle the impedance changes in the esl-63?

Thanks again.

Also, I didn't want to lead with this, but my sonic priorities lean more toward midrange magic and musicality. I am not one who seeks ultimate detail, "neutrality" in the audiophile sense, etc. I play at pretty moderate volumes, and never turn it up to extreme volume. So I am very curious about 300b and/or SET sound. But I am keeping my quads, so does this leave out SET entirely?
Another possible amp is an assemblage 300b push pull that might be fun to try. At 18 watts (I think) it should have enough oomph since it doesn't need to do much below 50hz?

Correction the assemblage is single ended and 8 watts. Looking at so many amps I got them confused.

Funny to see this old thread reactivated! I started it back in 2015. Lots of equipment under the bridge since then and I thought I would share my experiences.

Roberjerman is right... Single ended amps just didn't work with esl-63s. Usually dead on top. Other amps didn't work, such as Shindo, because they are made for 16 ohm loads and anything under 8 ohms is a real problem. The Quads literally blew amp resistors. However the sound was as good as I have ever had... stunningly beautiful, textured, real. Made most recordings sound like music.  It was a 30-watt Montrachet. 
Regarding power, I found even 30 watts can make great music, though be aware that I use Vandersteen 2wq subs so the bass dynamics were taken care of. Still, depending on your Sonic priorities, big power is not necessary. I also used VTL MB-185s on the Quads and they sounded absolutely amazing. The power does bring the macrodynamics to life in a very noticeable way. If your priority is mid-range musicality and timbre and texture, power is less important. If you need great dynamics, then more power. But if macrodynamics are and/or bass are really that critical to you, maybe Quads are not the speaker for you. Even with big power esl-63s are no match for many dynamic speakers, in terms of macrodynamics.
I never thought I would sell my Quads but I did. I compared them head to head with a fully refurbished set of Snell Type A and preferred the Snell's. Now I run a VAC Renaissance 30/30 with the snells and Vandy 2wq's and the sound is the best I have had. But nothing does graceful treble like the esl-63s... I miss that!
 

Willemj, I also find it hard to swallow that all perceived differences in amplifier sound are due to issues like clipping. My biggest problem with statements like that is the same problem I have with the objectivist camp in general: it assumes we understand why amplifiers sound the way they do to our ear/brain interface. I don't think we know even a small fraction of that. So how can anyone assert that this or that is the sole cause of sonic differences in amplifiers? It presumes perfect knowledge no one has.

Willemj, you raise good points. And by the way I am sure you know much more about audio than I do, so I will not be making many technical arguments here. A couple of points/questions:

1. As you suggested may be the case, I think you and I have different objectives. I want a system that most effectively tricks my brain into thinking I am listening to a real musical performance, regardless of what distortions or equalizations or trickery is employed. Separately, I don't seek neutrality to a recording because so many recordings are not representative of the original event. I don't want to hear recording flaws perfectly,fine in all their  glory. These topics, though,  have sprouted arguments for decades so probably best we don't chase them here, eh?

2. Maybe this question is a less well-worn road, and I ask this because I am interested in the answer,  not because I am baiting or trying to set you up in any way for a punch line :) ... Couldn't two amps of differing architectures but that each measure flat and neutral (however you measure that), playing music in exactly the same system, sound different? I have read a number of times that playing a dynamic music signal is an entirely different game than is playing test signals. Test signal performance may not be entirely predictive of what happens with a dynamic signal. Is this true? And further, could not the interactions with other components cause the otherwise "measured-equal" amps to sound different because they may operate differently into the real-world speaker load, with real music?

Funny you mention equalization because my quads and subwoofers did create a 8 or 10 dB bump which I cured very adequately with the use of a Rives Parc equalizer. Like magic. So I did use subs with my quads and totally agree they can be well integrated with esl-63s if you have the right subs and the right crossovers... in my case I used Vandersteen 2wq subs with the MH-5 ( I always get the model number a little wrong but it's the ones used in Vandersteen 5 system). Really amazing.

 I swore off solid state amps (it would be fun to ABX someday and see if solid state could fool me) though, I, I I am a believer that, in general, it is about execution and not about materials or topolology!)... But I had a great experience with subs and esl-63s because I lucked out and found subs that are fast and have pretty brilliant xover approach.
Someday I may go back to quads... They do things few speakers do in the treble region,  in my view. Peter Walker was a genius, and Peter Snell too. I should lobby to have my first grandson named Peter.

Did your listening test with Peter include tube amps, or was that the time period when tube amps were out of Vogue?

If you decide not to complete the updating yourself I recommend Kent McCollum at Electrostatic Solutions for Quad rebuild. I bought mine from him and had.a great experience.

Have fun with those quads.

I know nearly nothing technically, compared to Atmasphere, but my experience certainly confirms what he said. I have owned many amps that I imagine most people would consider well-designed, and they sound so different from one another. I know this is an age-old debate, but I have always assumed that there are measurable differences that we just have not figured out how to.measure, such a s a measurement that would gauge how an amp performs with music vs test signals. 

Atmasphere, do you think the differences could be measured someday, but we have not figured it out yet?

 here is Kent email if you want to try that: esolution@estatsolution.com

that's great Tomic. Kent is the man.

Though I have heard fried dog is underrated.