S-Video Failings.

Having recently decided to squeeze all of my older consoles into one entertainment setup (complete with an unnecessarily heavily HD CRT TV), I found myself wondering if my video quality could be improved beyond the standard yellow, red and white RCA connections.

The simplest option seemed to be s-video. The CRT boasted an input on the the front-side panel, and I figured a basic RCA to s-video adapter should do the trick. 

Three-way RCA splitter (S-video in yellow output) 
The first adapter I tried was from Radioshack. I ran the yellow RCA signal from the three-way splitter output to the s-video input and fired up the Nintendo 64. 

It was immediately disappointing. I'd been irritated by my N64's video output for a while, first thinking it to be an issue with cartridge or cables and then gradually realizing that the signal was always a little messy with RCA; graphics from games like Ocarina of Time or Goldeneye were only crisp in my memories, and I'd been spoiled by HDMI.   
But this s-video. Good god. The signal was definitely tighter, even sharper than RCA, but it seemed overlaid on a cross-cross texture. This grid-like pattern was clearly visible in all signals relayed from the three-way splitter to the s-video input. The issue was painfully apparent on N64 and Playstation; less so on Original Xbox and Playstation 2.  

Here's the RCA comparison:  
 RCwhat I mean?
Dismayed, I tried to find a solution online. Details on s-video as it pertained to older consoles were sparse, but I found a few tidbits which suggested that the grid texture was the result of poor assembly, indeed low shielding, within the cable itself. 

I returned the Radioshack cable the next day and ordered an ostensibly better-quality adapter from Cables To GO, via Amazon.

The replacement arrived this afternoon, and I giddily plugged it in. 

  The grid was still quite visible on N64, so I switched up to the Xbox to make sure I wasn't just being picky. 
Here's a comparison of menu text on the Original Xbox: 

S-Video, LEGO Star Wars menu 

RCA signal, LEGO Star Wars menu 
 And on Playstation: 
S-Video, Bushido Blade 
RCA signal, Bushido Blade 
 I'm out of my element here. Am I missing something, GB Experts? S-Video should be superior to RCA, right? Since two different cables from two different manufacturers have produced the same result, I'm doubtful that poor quality is an issue. It could be an issue with the s-video input itself, but the issue is only put into more horrifying detail on my LCD TV. 

Suggestions? Mockery? I'm just looking to get the best image out of my older games.

Thanks in advance.