amp for Gradient SW-63

Can you recommend power amp for Gradient SW-63? My main speaker is Quad ESL-63 (restore and mod by Electrostatic soultion), driven by JC Verdier 275D. Pre amp is Klimo Merlin
Thanks for advice
I use dual mono pair ARC Classic 150's for my ESL-63 & dual mono Classic 120's for the SW-63.
The Gradient crossover is the weak point IMO in this set-up.