The JAR800S was made to be a slightly different character from the JAR800.
It was aimed to maintain is slightly warm character over stock while helping its ability to resolve treble.
I found that Sennheiser had made some design decisions that increased bass but unfortunately made the 800S more sibilant in certain frequencies. Basically, the 800S lost its ability to resolve in return for an increase in bass and a shift in tonality.
So, my objective was to help maintain the 800S its character as per Sennheiser, but help it resolve just as well as the previous 800.