They're running from Rotel RMB1575 at the moment which is being fed by an Audiolab 8200AP. I have my Sonos ZP90 plugged digitally into the AP, so all my testing at the moment is via Napster (128kbps). My NAS drive is at work, but I might bring it home next week so I can try them out with better quality music. I have just picked up a Yamaha MXD1 digital power amp to try the front pair with, so this may tempt me to go 7.1. As the Yamaha was a £3k power amp back in its day, I'm hoping it'll do a better job than the Rotel, so the LS50's will sound better and I can turn the 1575 off when I'm not using it. I've compared it briefly against a £5k power amp at work and it seemed to hold its own....
Naim and Audiolab both work very well with the KEF's, so it is worth auditioning both to see which you prefer, but I would generally stick to same manufacturer components where Naim is concerned. And the better the power you can give them, the better the end result will be. This may not be a particularly expensive speaker, but its a high quality one, and it will respond well to quality amplification.
As I'm on the thread - I had a listen to them today in the demo room driven by a Leema Elememts amplifier and CD - extremely impressive with the Foo's latest album and Nirvana's Nevermind. It didn't matter how busy the music got, it was all there. I won't go on, because I've already said it all earlier in the thread...