Daniel here (Amfibius's friend). Congrats on your ESL's! Valves are ideal for ESL's as they are inherently a voltage amplifier (SS are current amplifiers), and that's exactly what electrostatics need. Whilst solid states amps start to get a bit shut-in due to some of the high impedences, the valves just eat it up.
I'd suggest a good well designed 50watt PushPull amplifier. Don't waste your time with 8watt SE amp's, you don't need their exagerated top end to hear detail on QUAD's, but you do need some power and drive.
Sometime in 2007 I'll be in the process of having a push pull 300B type amplifier made using Emission Labs 520B (http://www.emissionlabs.com/datasheets/EML520B.htm). Its an oversise 300B tube which should get my 50 watt per channel of triode power. Going to specify the use of the transformer based phase splitter. If you don't know anyone who can build you a custom made valve amp, look up Sun Audio.
They have a 20w PP 300B amplifier (http://www2.big.or.jp/~sunaudio/sv/sv300bmk2_e.html) and a lovely pre-amp. All tamura iron etc.. yummm!!!
Cheers,
Daniel.
PS. I post on Audio Asylum as SnaggS if you want to contact me.