MKP is a type of cap (polypropylene), but not a specific brand. :) The Mundorf MKP caps are pretty darkish/warmish, but very good low level detail.
The Supreme's -> Supreme SIO are colorful in the mid-treble, almost over saturating. Not unpleasant, but definitely euphonic.
I would try Audyn TrueCopper or Jupiter Copper caps as your high end copper foil caps. Audyn is limited to 2uF or so.

