Here is an easy to install kit that will give your current version V2.1 S.E.X. kit a more quiet background, better resolution and tighter bass. This kit has been available in the past for previous versions, but we have updated the PC board and the mounting setup to make a cleaner installation.
 
This morning I swapped my SEX3.0.1 into my office system so I can do some maintenance on my SEX2.1.1. (I listen to it all day, every day that I'm here) When I built the 3.0.1 it soon got the C4S board, while I never installed the C4S in the rebuild of the 2.1.1. This is the closest to an A/B I've done and the difference is very noticeable. Not blessed with golden ears, I'll just say the grin was almost immediate. And part of the maintenance on the 2.1.2 will include installing the C4S board! Thanks again Doc and crew.
 
The newer 3.0 version of the S.E.X. kit has a slightly different kit here.