Power amps for Quad electrostatics 2905

Quad 909 might be nice

After 20 years of Quad experimentation, the Esoteric Audio Research 509 gets my vote. Effortless and neutral when much higher powered amps suffered. The capacitive load probably won't work with any Class D amps because of the feedback scheme. Both aforementioned amps have tertiary feedback windings in the outputs. Those windings prevent the feedback from getting out of phase due to the capacitive nature of ESLs -if I understand it. Otherwise, the best Class A sand amp you care to buy. I have an old Bedini 100/100 workhorse from the eighties that I keep around just because of this. It is not as transparent as some of the modern amps, but handles the load with aplomb and works in a pinch. BTW, the Bedini 25/25 was hot with the 57s back then...

I tried Nuforce 9.02's with my Quad 63 USA's just prior to selling the Quads. It was not a good match in my system either. Made the Quads almost dull and lifeless...I have used various tube amps with the Quads.from low watt El-34 and 845 SET to 60W Kt-88 amps..all with excellent results..the best amp I used on my Quads was an older Threshold S/200..just a perfect synergy of balance, warmth, and transparency with enough power to grip the panels. I also used an older Class A Bedini BA-801 that worked great too.

Im not sure if Class D amps are the problem. Another AgoN memeber who runs Quad 989's runs a pair of Channel Island Audio D-200 monoblocks and they seem to do just fine..Maybe its the Nuforce amps in particular..dont know. But they did not work well on my Quads.

I have them on my Emerald Physics speakers now with exceptional sound.

I use a Pass Aleph 30 for my 2805s, it is plenty powerful in my apartment but you may require more power. I have an EAR tube amp as well, but I prefer the Aleph (this was a little surprising when I tried).

There is just a natural synergy between tube amps and quads.Class D amplification has its merits but not with Quad speakers.