I do have an S-Video cable too (turns out new-in-box OEM S-Video cables only cost $10 USD on Amazon, since it's the same cable for PS1/PS2/PS3), but due to big delays in shipping I already had the RGB cables by the time they arrived, so I've not bothered to try them. From what I've seen, the S-Video cables look much closer to RGB than composite, primarily in how they get rid of the horizontal blur that the PSX seems to have on composite.




