This weekend I've tried my CD5x without being connected to the Flatcap 2x.
Having played through a number of cd's there's a noticeable difference once the Flatcap 2x removed. The sound is presented with a greater richness to the tone and noticeably more heft in the bass, with kick drum and bass a little more evident. Reconnecting the Flatcap made the sound appear a little brighter and leaner sounding but also lost the nice richness that I was getting without the Flatcap.
Im going to spend a bit more time listening without the CD5x connected to the Flatcap 2X, just to be sure of my findings.
Just wondered what differences other users may have heard having tried with and without an external power supply connected to their CD player.