I wish I had access to a CS-80! Tough I understand what you mean, the thinning is also due to EQing, as each slider must provide room for the others in the mix (so they each are equalized, similar to mastering). So, it was deliberate from me. The middle slider, for example, is anything but thin :
https://mynoise.net/NoiseMachines/november2019SoundscapeGene...
