I remember a significant audio quality upgrade when I moved from 565 to 568. I can't say how much of this was down to hardware, or how much was a change in setup/configuration. I went 565/508 to 568/596/508 - the 508 soon became redundant and 568/596 eventually upgraded to 568.2mm/598DP. The latter was probably my 'peak Meridian' even though I latter had G68/G98.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).