The datasheet clearly specifies a 24+51 divider at each input so that’s what I did.
From ADV7280 (video) datasheet:
The audio chip accepts 3Vpp, but most retro consoles output way more than that.
Do the same with audio inputs but 10k+10k, the 10k to ground is already there.
This will accept even the loudest console without clipping like the N64 which outputs a huge 6Vpp, and will bring the overall volume to standard set-top/satellite box levels.
Here’s how my mod looks (there are more resistors on the back for s-video not shown in the photo), it fixed all audio+video problems.
I could have used SMD resistors but, I only had the correct values in through-hole 1/4w size.
Don’t mind the dangling oscillator in the photo, my RT2x is dead from a power surge and I’m trying to revive it.
NOTE this will void your warranty, since it involves cutting traces on the PCB.
To be frank, the RT2x does not worth 100$ with the current flaws.
I really hope Mike Chi fixes both audio and video inputs in the next revision.
I also did not have color in Composite/S-Video with my modded PAL PS1 which runs in PAL60/NTSC4.43 mode when booting NTSC games.
The ADV7280 chip supports both these formats according to spec sheet and should produce color with this signal.
Maybe Mike turned these modes off, when I asked him about it I got no reply.