Get a used Krell FPB cx amp. They work very well with tube pres, have all the power you'll need and last forever. My 300cx is almost 10 years old and has never had even a hiccup, sounds grand with my Wyetech Opal tube pre. Always looking to upgrade but I cannot find anything here that requires upgrading, other than tube rolling and installing Teflon caps in pre.
Neal
Neal