I had some time to kill, so I have fitted a DIP8 socket to the PCB, and installed a Burson V6 Vivid in it.
As the case was open, I also lost the standard captive power lead, and fitted the spare Mark Grant DSP2.5 I had, soldering the end directly to the CDP input.

The best thing is that I have put it all back together and it still works.
Spinning my first CD, Faithless - To all new arrivals and it sounds superb. No idea if it is much different from before, but the bass “seems more powerful.”
I am quite happy with the mods, and I am now tempted by a clock upgrade, but ideally would need to find some instructions on how to do this.