What amplifiers/integrateds do you like with Cornwall IVs?

First of all, there is no such thing as too much power even with the Cornwalls. Having said that and Atma Sphere S 30 will drive them handsomely. I would prefer the M60's which would really rock. They are Class A amps (the best) and avoid transformers which introduce a whole set of problems. They are also beautifully hand made. IMHO they are the best tube amps made and I am seriously considering a pair for myself. 

I might consider an Audio Note EL34 kit.  Loads of quality parts, single pair of el34 tubes, from what I have read quiet as a graveyard. Bet it would be a great match and a blast to build if you enjoy that type of thing.  They occasionally have sales to boot

https://ankaudiokits.com/2/EL34-IE-Core-C-Core-Integrated-Power-Amplifier.html

Update--

So 30 hours of straight play from the Music Hall Class A Mambo, and I swapped in the Primaluna HP Integrated, running KT 150s and reissue Gold Lion 12au7s (I have enough NOS 12au7s to last 100 years, and I think these are almost comparable to NOS, almost).  

Holy cannoli!  This is nuts how holographic and gorgeous this sounds.  

Um, two words-- "Classical Music!"  ---I hear it like never before.  These speakers could be a doorway to and place within the genre for me. 

OP, I know you just swapped but can you pick a winner between the PL and the class A on the CW4? Seems like you really liked both.