I had a sibilance issue that was driving me MAD for close to a year. I had my system sounding excellent (Innersound Eros stats and Innersound amps in those days). SOUNDED MAGNIFICENT so I decided to make 2 upgrades (at the same time). The bigger upgrade was replacing my Esoteric X03SE SACD Player with a new K03; at the same time, I purchased Symposium Svelt Shelves to go under the speakers.
BOY, did I have sibilance, which I attributed to the new SACD player requiring break in; also got it a new Shunyata $2,000 PC just in case that was giving me trouble. More time for break in. Making a very long story short; when I added the symposium svelt sheveles under the speakers, I did not realize I had to remove the metal feet under the speakers. I had spend thousands to try to find/remove the sibilance. Needles to say, once the feet were removed, it was heaven again.