Thanks witti.
Yay, this works in principle, cool. Wouldn't have thought of shifting the meters. However it's still a bit "unopolished".
Track 1 is both peak + RMS, track 2 is RMS (ch. 3+4) only with your code line pasted in (I'm using the v4 default theme).
It doesn't have to look perfectly nice for me, but any chance to get this working at least without not obscuring vol and pan sliders (and same height as default meters) than I'd be really happy.
As I'm not a themer (and have little knowledge regarding graphics stuff in general), before I now start a long-winded trial and error session, any suggestion for improvement ?