Intergrated Amps. Krell or Plinius

Fatigue will set in with the Krell. It is powerful but somewhat bright. The Plinius is a good amp but will also be a fatigue unit but not as quickly. The Mcintosh 6900 or 6850 would be more natural sounding and non-fatigue unit.
Just my two cents.

Then again there's the Simaudio, said to mate very well with the Dynaudio line. Try an used I5.

I owned a Krell 300i; haven't heard the 400. The lower-end Krell stuff is just not that musical, IMO. It's almost a no-brainer between a Plinius, & a Krell integrated.........the Plinius integrateds are very highly regarded.