Hi Steve and AC members, I have been experimenting with a sheet of thin self-adhesive grungebuster material on WBT RCA plugs and had good success. It looks cool and provides a nice soft grip as well, I sent some info to WBT suggesting to incorporate something like this in their design.
I tried a few configurations and ended up with two 1/8" wide strips of grungebuster applied in rings around the barrel of the RCA plug, one near the top and one near the base. The WBT barrels screw onto the body of the plug and are used as locking collets for the RCA plug, there are 2 layers... an inner and outer that can rotate independently. The inner stops rotating when it hits the three ground prongs and starts compressing them around the RCA jack, the outer continues to rotate to provide enough force to lock the plug into place.
I have noticed the biggest differences in vibration control on AC power and plan on experimenting with applying grungebuster to the plug bodies in the same way as the RCA plugs.
Too much damping can make the music seem dark and lifeless so if anyone wants to try this more is not necessarily better. Herbie's Audio Lab has material with the right properties which is important too, you want the right material in the right quantity and right placement so it takes some experimentation. When it's applied correctly the result is more neutral but not dark and lifeless.