The difference (in my experience) is mainly because I use my 818v3's balanced XLR outputs, which the 218 doesn't have. If using the SpeakerLink outputs into DSP7200SEs, there was no audible difference.

I've not tried using the 218's inputs as 99% of my listening is through Roon (using Tidal). I suspect there won't be a difference when going to DSP speakers.

The only 'compromise' would be the 218's analogue output compared to the 818v3's analogue outputs.

After I had modified the first 218 I really thought I'd gotten some wires crossed but into DSPs the LPSU conversion could possibly exceed the 818v3 (with the right LPSU)!

You only have to take a look at the small matchbox 'brick' that is the internal PSU in the 218 to realise how much you can improve things.

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.