Best amp for Thiel 3.6 speakers?

I am looking to replace my existing amp, a 250wpc NAD 218 THX, with something that works better with my large Thiel speakers. The 218 has plenty of power to drive these speakers but I would like to upgrade to a better amp.

If there are any other 3.6 owners out there or just someone with an experienced opinion on a good upgrade I would appreciate any feedback you can provide.

Thanks,

Montana Rane