[Higgy]

Ah! Sorry I missed the fact I had to press F2. So I press F2 and then the On-Screen RPi menu disappears and I will have the AMIGA's output straight through the GBS- video chip!

I had the keyboard connected and I had a look at the onscreen menu. Quite a lot of adjustment there!
Maybe you could add some text to the On-Screen menu if you update it, for us that don't read the txt 'Press F2 on RPi keyboard to switch output to GBS- ' or something.

So the AMIGA would be a RGBHV 2??p not a YPbPr? I guess.

I look forward to playing again with this then this evening. Many thanks.

NOTE - just to clarify/mention in case this has not been tested as not quite sure how Megadrives etc have been connected.
I am connecting the AMIGA to the GBS- via the RGB header. So I have a SCART cable from the AMIGA going into the GBS-. I wired a female SCART connector onto the plug supplied with the GBS- that goes into the RGB header.