Is it possible the CD player passes both a full analog unfold PCM signal, and SPDIF 96K PCM first unfold, which would contain the data necessary to be further unfolded in SEs?

I think, this is consistent with comments in the lengthy 218 usage thread, and the spec sheet here referenced, as to input performance of the 218 inputs.

James
NC1: 861v8, ID41, 218, 251(to outdoors), DSP8000SEUG, 7200SEC, DSP520 rears, Apple TV, DirecTV, Oppo BD103, QNAP251, Roon
NC2-M7005, Triad Silver Speakers,Acurus Amps

FL1: 861v4, ID40, 218, MS200, DSP8000SEs, DSP7200SEC, DSP5000s, DirecTv, AppleTv, OppoBD103, QNAP469, Roon
FL2: Marantz 7005, 251, M60s,60C,33s, Oppo BDP-93,MS200, Roon