tonywinga,
I understand now what you meant by bass improvement. Most people just mean more or harder impact and subs will do both for you.
I am listening to the Stanley Clarke “East River Drive” album now listening for what you describe (new music to me thanks!). It is very subtle and I wonder if that “skin” sound is actually a little higher up in frequency as a secondary sound.
I turned off my subs and high-passed the mains at 135hz and I feel like I could still hear it. Broke out the digital EQ and it might be in the 200-500k range. Hard to say and the detail is very low level.
I switched over to a pair of Grado PS500e which I often hear that type of stuff on. I could hear it on the headphones but it did not stand out any more. I expected it too on headphones as they are more detailed in the bass.
I think this type of detail retrieval is getting into super speaker territory and will cost a lot of money lol.
Heavy room treatments (I see you have treated a bit already) with wide band absorption on the side walls might help pull that kind of stuff out more. Something like a high number of GIK 244 panels or even something thicker as reflection panels to knock down the bass reverb.
