FWIW, I had an amplifier module here for review over the last while. SQ with my ESL57s was excellent - and I mean excellent.
http://tirnahifi.org/reviews/?page_id=207
Might be something to consider down the line if you do go the route of quads.
Fran
Quad ESL63
Re: Quad ESL63
Do or do not, there is no try