thinking of switching from conrad johnson......

trying to decide between pass x250.8 or plinius sb 30, was looking at the cj premier 350 or the McCormack dna 500, but these amps are getting a little long in the tooth.  any suggestion and your experience with these two amps would help.  and what pre amp would work best with them.  since not many preamp companies are left.  and any feedback from whilecamaross is very much welcomed......thanks in advance.