I really have no idea how to proceed. I will run the speakers in fully and may well try my Cambridge SR20 amp and use the coaxial from the CD to bypass the Rotel CD11s internal DAC. The SR20 is pretty warm, and powerful (100w per channel into 8ohm) but not especially refined. If the issue persists, then I'll decide then what to do.Perhaps Rega could sort the problem. Rega midrange is thick, not bright top end either.
It could work because of MA extremely detailed highs. Marantz probably also. Even Denon.
I suggest the Rega Elicit R, Marantz PM8006, Denon 1600NE.