The Meridian Prime PSU would definitely be an improvement on what is fitted at the factory...

Here is a link to a similar PSU module - https://www.farnell.com/datasheets/2547883.pdf
It is really tiny...!

Converting to an external PSU ensures that there is no mains voltages or interference inside the unit and is always reversible.
The same modification can be carried out to the 210.

Main: 861v6 (LPS), 808v6, UHD722, DSP8000SE Anniversaries, DSP5200.2HC, DSP7200.2, SW1600, Sky Q, Cambridge Audio BD, Roon, M80
Office: 861v4 (LPS), 818v3, 800v4, HD621, M&K S150P, DSP5500HC, M&K MPS2810 sub x2
Son's system: 861v4, HD621, DSP6000.2, DSP5200HC, DSP33
Spare: MCD, 100 Series, 200 Series, 500 Series, F80s, C15s.