Just my "personal" opinion here, but I heard them side by side and preferred the older one box CDP by a fairly wide margin. As you may know, many people attribute the lion's share of the Reimyo CDP's wonderful sonics to the older (no longer made) JVC transport. The CDP incorporates both the JVC K2 processor and the actual transport mechanism used during the mastering of JVC's XRCD² recordings. The stand alone units do not. From what I understand the DAC in the one-box CDP is a higher bit DAC than used in the separates (I think its 24 versus 20 bit).
This all translated IMHO into, among other things, less jitter, better midrange, better resolution, lower noise and more natural timbre - but, as always YMMV.
This all translated IMHO into, among other things, less jitter, better midrange, better resolution, lower noise and more natural timbre - but, as always YMMV.