ESL57 vs ESL63

The 57’s are going for twice the price of 63’s.

i like the managable size of this speaker, this is really a part of my soon to be retirement built two channel system.

besides the price, how do these two fair amongst each other. Realistically how much power do the require, tubes ? Solidstate ?

my hope would be to also get into lower powered triode type amps with this projects.....