So as the tittle says, I am curious to weather a full sized neck pocket shim, made from inserting a plastic credit card in the neck pocket, to some extend might dampen the vibrations from the strings, and thereby sound of a bass? I am asking cause that is what I currently have in my main bass, to allow for sufficiently low string action without having the saddles sit flat on the bridge plate. Now I don't really have any issues as such, the heel of the neck sits absolutely tight in the neck pocket with absolutely no excess space to either side, and I really have no complains about the sustain of the notes, neither acoustically or amplified, just curious really, and wonder if I could possibly expect any improvements if I was to swap out the plastic credit card shim with one made out of metal or wood instead? Edit!!! - performed a test : I decided to do a test myself, pressing the end of the headstock of my bass against the tabletop of a wooden table to amplify the acoustic sound of my bass, respectively with the headstock pressed directly against the wood and then with a plastic credit card placed between the headstock and the wood, and from what I could hear, trying my best to press the exact same area of the headstock against the exact same area of the wooden tabletop, applying as close a possible to the same amount of pressure, and plucking the strings the same place and with approximately the same strength, I didn't notice any difference whatsoever, neither in terms of volume, sustain or tone, which would imply that using a full sized plastic credit card neck pocket shim likely won't dampen or otherwise affect the vibration of the strings and sound of a bass, at least not in any noteworthy way. Still interested in hearing what people has to say on this matter though, my test was hardly strictly scientific or fool proof.