from a Krell SS- FPB 600 to What Tube Amp ?

I have been a Krell listener for 15 years, from the KSA-150 to the FPB 300 ,to now the FPB 600. I love the Power in Class A, and the great Bass that the Krell offers. But I think I maybe missing out here on some great tube amps. I think it is time to give a reasonable audition to some Tube Amps. IF I could please get some experienced answers , that would be much appreciated, like someone who has gone threw this transition . I know all the names of the best tube amps, but getting someone who has experienced this is very valuable to me. My budget is $5K- $8K used prefered, $$lower also works.

My System:

Meitner-EMM Labs DCC2 + Phillips cdp D.O.M ( Truly Amazing )
Kubala Emotion cables, all cables (***** Truly Amazing )
Walker Velociter ( Great Stuff )
Infinity MTS Preludes, 6 Ohms (also need to change)
Townshend Super Tweeters ( Great Stuff )
Krell FPB-600