Quad 57 refurbishers - who's the best?

What's the best company for refurbishing Quad 57s and/or selling refurbished Quad 57s?

Apparently so, on this continent anyway.
Where the Quads strength lie not much even today can start to come close.
Mothra, I don't have the quads right now. I'm looking for a pair and wondering whether to buy already refurbished or take a chance on a used pair and have them sent directly from the seller to the refurbisher.