@stuartk
Switching from a Moon 260 DT to a Jay’s CDT2MK3 resulted in a very noticeable improvement
With respect, from my reading of the CDT2MK3, it outputs using I2S over an HDMI cable. This is not a native HDMI implementation!
I2S performs no error detection and no error correction. It was originally designed by Philips in 1986 to allow two chips on the same board to pass 2-channel 16-bit PCM signals.
Presumably to avoid paying HDMI licence fees, I2S is now being fed into HDMI sockets and then HDMI cables to transfer 2-channel digital between boxes.
The lack of any error detection or correction means that cable lengths should be kept to a bare minimum. If this is not a warning, I don't know what would be. The fundamental proposition for digital is that errors can be detected and corrected
So in view of the lack of error detection, let alone correction, I am not surprised that transports using I2S may sound different, but I agree with @malbers original proposition that only the separate DAC really matters for CD transports (with the qualification that they must natively output HDMI or similar)