ESL57 vs ESL63

Can’t give you a comparison but the 57s needed a fair bit of SS power. I don’t think my Naim amps ever worked so hard before the Quads arrived.

After reading nothing but praise for them I went to a lot of trouble to get a pair but they didn’t stay long. Sure, with the right recording and the right alignment of the stars they might be capable of stunning vocal reproduction and imagery but...they do need a lot of fuss as well as lots and lots of space.

The final straw broke when I played some Rock through them and received an entirely lacklustre result. One for Classical and Opera fans foremost I think.

I never heard the 63s but did catch the updated 988s I think, (could have been the 989s) and once again was left feeling underwhelmed.

They do some things deliciously but don’t seem to be a speaker for all genres. Far from it.

On the plus side it was always easy to move them on as demand was always high. 

The 57's and 63's still hold their place as the very nearly best speakers ever! Peter Walker's marvels! I have two pairs of 57's. This gives me the option of stacking them for improved image height. Regarding power requirements, both the 57 and 63 work best with 25 to 50 watt amps. This rules out flea- watt SET's. A Dynaco ST70 is an excellent choice for either. Since both have quite extreme impedance curves (30 ohms to 1 ohm) a partnering amp should have a low output impedance (<1 ohm) for best response. Both are voltage-limited because of arcing (20 volts/50 watts for the 57's, 30 volts/90 watts for the 63's). Because of these limits there is no need for high-power amps (risk of damage to the Mylar diaphragms). 

I have a variety of tube and SS amps to use with my 57's: Dynaco ST70, Heath W5's, Golden Tube SE40, Futterman H3 and H3aa's, Quad 303, 50's, 405, GAS Son and Grandson, BEL 1001 ...