Amplification for stacked quads?


Hello I have a pair of wonderful stacked ESL 57. Right now I am running them with a pair of EAR 509MKII monoblocks (100WPC) but I am considering Berning's ZH-230 (30 WPC) and the integrated Jadis DA-60 (60WPC). Has anyone had experience with stacked quads? Any recommendations in general? And how about the amps I mention here? Many thanks.
ggavetti
What don't you like about the EAR's on the Quads? Not a very practical recommendation, but to this day one of the most memorable systems I have heard was stacked Quads driven by Levinson ML-2 class A mono's; and I typically prefer tubes.
I like them a lot. It's just that not having other reference points I don't know if I am missing something. And I have always been a big fan of Berning. But certainly the 509's are quite good.