I am a quality treble freak. The treble has to be clean and grain free, not etched or distorted or i am not happy.
My prior amp, Forte'4a was decent, but my new amp, Bryston 4B-SST2 is better.
I do have it on a Furman REF20i conditioner.
The amp is transparent, so digital stuff i do have it via VAC Standard preamp i use as a glorified tube buffer.
If the op has never found a SS amp which is good, I would start looking at the source, or the power besides the amp itself.
Anyway, the 'squared' Bryston amps really have treble issues solved.
Try any class A biased, low-to-mid power, SS amp.
Electro monos, the small Plinius... Any well maintained vintage class A amp probably could bring on happiness.
Another good if unlikely candidate is a wide bandwidth amp: Spectral for example.
Stay away from Krell, M-Lev, & the like. Accuphase would probably not fit the bill either.
I'm guessing you don't really needed a "muted" amp -- just one that doesn't sound shrill to you in the 2-6kHz region... After all, well designed tube amps reproduce high frequencies very well indeed, so if these frequencies are muted you'll miss them... even if the 57s don't go up very high.
I have actually enjoyed 57s with class A SS amp, hence the blurb above.
The top 3 models of the Crown Drivecore series are quiet, cheap and sound good with gobs of power. They can drive 2 ohm loads so you won't have problems driving whatever difficult speakers you might be reviewing. Just turn off the limiters and crossovers and don't overdrive your speakers.
I think this is a better way to go, rather than getting something underpowered (not versatile if you keep changing speakers) or old (that will need maintenance)
Not sure that you are asking the right question. I think that the right question would be what solid state amplifiers would be a good sonic match, and avoid excessive brightness, with YOUR speakers.
The reason I say that is that in comparison with most tube amps, most solid state amps will tend towards brightness with those particular speakers, due to the interaction between their much lower output impedance and the impedance characteristics of the speakers, shown here and here. The Quad's huge impedance decrease that occurs as frequency increases, and the low impedance of the Maggies at high frequencies in comparison with its large impedance peak in the lower midrange, will cause an amplifier having low output impedance/high damping factor (such as most solid state amps) to sound brighter than one having higher output impedance/lower damping factor (such as most tube amps).
That said, back in the day the famous Mark Levinson HQD system paired his ML-2 pure Class A 25 watt amplifiers, having huge current capability, with the ESL-57 (and a separate woofer and high frequency tweeter). Perhaps the Pass XA30.5 would be a comparably suitable choice today. Some of the higher powered amps in the XA series, as were suggested above, may also be good choices, while perhaps also being better suited to the Maggies, but you would have to be careful to avoid overdriving and possibly damaging the Quads.
I have the Quad 57's in a "second system", and haven't wanted to spend to much on other components. After reviewing the experience of others, I found that the VTL Tiny Triodes pair very well (tube amps), and the Bedini 25/25 pairs well for solid state. No treble harshness there. Relative to the VTL, a small loss in midrange magic but a firmer bass. If you are having hardness with the Bedini, I think the issue might be something else. I've heard that the Pass Aleph 3 pairs pretty well too, but the Bedini is better. Quads and Maggies have very different amplification needs.
I have both the esl57 and mg1.6! 909 works fine with both of them. But, it is difficult to find the pre that matches, since Quad 99 is not up to task,while input impedance (20k) of the 909 is not quite comfortable for tube pre. After 10 years of trying different preamps i ended with passive one:
Mr. Tennis, just wondering... when you do find this amp and do a review, how will you describe it? ..." a wonderful amp, excellent mid range,iron fisted bass control,and beautifully rolled off, recessed treble "? I think you need to look elsewhere in your system if all solid state amps sound shrill and aggresive. Just wondering...
I am now using VTL Deluxe 500 mono tube amps now. Before this, I had used the VTL 225 monos. And before that, a Levinson 27. The Levinson 27 (or the more powerful 23 in that series) is a very warm sounding solid state amp. I had tried a Levinson 333, but it sounded too analytical. If I were to go back to solid state, I'd consider the Levinson 27, or 23, again.
I want to stress again that Electrocompaniet amps will float your boat. I am 100 percent confident you will be contented with any of their newer models. Just depends on how much power you want.
They are THE closest thing to your wonderful tube amp that you will find in the SS camp. They will not attack you with details, but rather they let the music flow for you to enjoy.
I own an Aesthetix Atlas hybrid amp and it also sounds most pleasing. It does however have two 6sn7 tubes and is hard to find used.
I would try the Rogue Atlas that Mark makes special for Quad owners. It's the best amp of about 15 that I've tried with ESL57 and I know it can run Maggies. I heard it with 1.7s and the combo sounded great. Call Mark at Rogue and discuss. He's really helpful. I fitted mine with KT120s and it's the component I'll never sell.... well until I get a TON of money :)
The problem has three elements. If you have ever wondered why a tube amp and a transistor amp can have the same bandwidth but the transistor amp sounds bright here's why:
Our ears are tuned to listen for the odd ordered harmonics in order to determine the loudness or volume of the sound. When electronics distort these harmonics it will sound bright to us. BTW, our ears are also tuned to be the most sensitive to **bird song** frequencies, not the human voice!
Now when you add negative feedback to an amplifier you will subtly increase the odd-ordered harmonics. Most transistor amps (not all) use this technique to improve linearity. In addition, nearly all semiconductors have a non-linear capacitance that exists in the junction of their devices. This capacitance is also responsible for adding to the odd-ordered harmonic distortion.
Now the odd orders that we are talking about are very slight, but it happens that the ear is very sensitive to this issue.
Finally, on a speaker like the Quad ESL 57 or ESL 63, the speaker really prefers an amplifier that does not double its power as impedance is halved; both of these designs existed before such was common. So a transistor amplifier, if it is behaving like a voltage source, will be bright on these particular speakers even if no odd-ordered harmonic distortion were present. for more info regarding this phenomena:
McIntosh MS501 monoblocks are worth considering. I owned them for a while to tame some speakers I found a little too hot in the treble. These are rich, powerful SS amps with a warm, tubey quality and attractive midrange. The treble is all there but slightly recessed. They have multiple output taps, like many tube amps, to meet the impedance needs of different speakers.
I think you should review/try the Coda equipment. The guys at Coda seem to build a very relaxed solid state amp. The #15 might really be something you'd like.
A lot of solid state amps can start sounding harsh if not given their own direct line. They are little piggies about current and don't like to share.
In my experience the Levinsons, Krells, and Codas are very much this way.
I would tend to think this phenomenon is the rule for getting the best from solid state.
Another way to keep odd-ordered harmonics down in a transistor amplifier is to increase the impedance of the load.
(This BTW, is why there really is no argument for four-ohm speaker designs, not if the quality of reproduction is your goal- if **sound pressure** is your goal then have at it.)
The Quad is thus unsuitable for although its impedance is high at bass frequencies it is quite low in the upper mids and treble region. This is one of the reasons why ESLs and transistors usually don't play well together.