Recommend an amp + pre for ESL 57s and a new turntable (way out of my league)

The Aragon sounded great on my 989s.  I think the Bedini is a great choice.  It was easy to replace caps and still sounded great.  Let us know what you decide. 

I've tried a number of amps with my 57's- I won't contradict any of the above advice, it's all reasonable. Just adding my experience to it.

My pair was refurbished by One Thing Audio, so the treble response is somewhat extended, and a "clamp board" was added, which lessens the risk posed by overpowering them. Nevertheless, definitely stay away from the types of SS amps cited above, as those amps could fry. 

Some good vintage tube amps aren't optimal, in my experience. Heathkit UAD-1's, highly recommended by some, are too weak. In a well-damped listening space they break up at volume. Getting above 20W or thereabouts really helps. Good transformers- very good transformers- also makes a difference. My Eico HF-81, while great with many speakers, didn't cut it with the 57's. The midrange is great, but the "grip" on the bass is lacking. A Scott 299B also didn't fare well. Neither did an Anthem Integrated One- enough power, great midrange, but poor bass control. Don't even try SET's. A Bedini 25/25 (pure class-A , runs hot) cleaned up the bass and sounded pretty good, but I was tempted to try a Rogue Atlas, as a "shoot-out" featured on a website between many respected contenders had that amp placed second behind a rare boutique German ASR Emitter (sic). I sprang for a used example (not too expensive) and was finally almost satisfied. All previous issues were vanquished- it sounded really good. My next challenge was to try to fill in the lower bass frequencies that the Quads have trouble with. I tried gently supplementing them with a good sub, but it was hard to get it to feel right. So I switched the KT-88 tubes for KT120's, which definitely helped, without fouling up the midrange magic. I also put them on custom stands to raise them about 18" and make them easier to "aim" the sweetspot, which actually matters more than most amp-matching questions. I'm still curious how a Radford or a Futterman might sound, but I'm skeptical the effort to find great examples of these would be worth it.

I can sum up by saying 57's are very amp-dependent, and even those with glowing testimonials may not be best. Experimentation and patience are worth it. Be careful- once you get them dialed in you'll get obsessed with upstream improvements, as you'll really be able to hear the difference they make.

@imintohifi  Indeed. I use modified and refurbished EICO HT-35 (monoblocs) under each ’57. They are superb and respond well to good tubes.

@pindac Surprised to hear that. I tried mine on 4,8, and 16 and found 4 muffled and distorted, while 8 ohms was merely lifeless. 16 ohms is perfect. Maybe theirs were in series and yours are wired in parallel,

I hear the 57’s as a Stacked Array used at 16 Ohm when driven by a Sansui AU 111.

I never detect anything that suggests there is something quite different to my own stacked Array used at 8 Ohm.

Eico HF35’s at more than twice the power and with iron heftier than the HF81- sounds like a really good choice!

We have a number of customers using our S-30 with the old Quads.

@clio09 used to use our M-60s (a bit over-powered) with his.

No worries about what tap to use since OTLs have no output transformer. 

The advantage an OTL has is the higher impedances in the bass, which make the speaker difficult to drive with a lot of amps, do not cause appreciable loss of power. 

On this account I think is why long before I ever got into business, I had heard that Quads and OTLs were the match made in heaven. You do have to be careful with them though, as most OTLs can easily overpower the speaker.  

If the '57s are in good shape, they easily justify a good amplifier. They are quite revealing which is why the speaker is still taken quite seriously even though the design dates (and often the manufacturing dates too) to the 1950s.

The Dynaco ST35, as well as the RM-9 or RM-10 of Modjeski fame, are also excellent amps for this speaker. The older ST35s from the 1960s have 8 and 16 Ohm taps. The newer ones have 8 and 4 Ohms. 

The Sansui AU111 is a very competent amp too- if you don't mind using an integrated amp. It was so good Sansui reproduced it in the 1990s.