Help matching am to Kef 104/2

Hello all,

I am considering going to an all tube integrated amplifier to push my Kef 104/2’s. At the moment I am using a Rogue Sphinx 2 and they sound great to my ears. I still think these speakers have a lot more to give with the right amp. My budget is under $4000. I am looking at Rogue cronos or Primaluna but am open to others. I am concerned about spending the money and not getting a worthy increase in performance due to my lack of understanding when it comes to sensitivity(92db’s) and power requirements. I have read article after article about sensitivity and have come to the conclusion that I am just not smart enough!! I am looking for warmth and soundstage.. My set up is in my living in an old house from the 1920’s and is less then ideal. Room treatments are not an option. Any help would be appreciated.

P.s. no I do not want to replace the speakers and anything over $4000 is out of the question regardless of promises of greatness.