You probably answered your own question already - you were awestruck by the KAV-400xi. If those are your three choices, the 400 is the one you're going to be happiest with.
Domestic tranquility certainly has value, but if you've put together and use the system you detail above, backing way off in the amp / preamp part of the system for looks is going to gnaw at you for a long time (or at least it would me). It's great that you're willing to try to find a middle ground, but I'd shoot for something that is 98-120% of what you currently have if music is a core part of your life enjoyment.
Domestic tranquility certainly has value, but if you've put together and use the system you detail above, backing way off in the amp / preamp part of the system for looks is going to gnaw at you for a long time (or at least it would me). It's great that you're willing to try to find a middle ground, but I'd shoot for something that is 98-120% of what you currently have if music is a core part of your life enjoyment.