I have had the 403 and now the 403e, I was also lucky enough to be @ Krell's demo of the 402 v 402e @ CES a couple years ago, the 'e' series are much smoother and cleaner, everyone in the room was equally impressed.
FWIW I have also owned a KSA 300 s and find the new 'e' series Evo's far more musical.
I have not compared the 400 mono's to the 403 or 403e however
FWIW I have also owned a KSA 300 s and find the new 'e' series Evo's far more musical.
I have not compared the 400 mono's to the 403 or 403e however