Input /output caps

Have seen for some time now that some manufactures use "sheilding" caps on the unused input/output jacks in an effort to reduce emi/rf and enhance sonic benefits. My question is has anyone one been using them and if so WAS there a preceviable sonic difference with them in use (as I realize that it could be subtle)? Becuse Cardas caps aren't that expensive and could be an inexpensive tweak for me to try then. Thanks for the input.