I did something slightly different, since I had a bunch of VGA switch-boxes around.
I've made a VGA cable for each machine I wanted to connect via RGB (currently: A500, Atari STE and soon Amstrad CPC & Sinclair 128/+2) and routed them through a 4-way mechanical VGA switcher.
The switcher is connected to my C=1084 via VGA->SCART cable.
Audio goes through a different switch-box to a stereo system.
Its all still WIP and I keep changing things around on a weekly basis...