When I upgraded my OB speakers crossovers I ended up with an external crossover. The cokecan sizes of Jupiter caps required using gasket sealer (recommended by Herbies Audio Lab) in lieu of other caulking type material for better sound quality.
Eventually I put some IsoAcoustics footers under the crossovers and did/do hear a difference. Not huge, but noticeable.
And more recently on some Tekton speakers that use 52 screws total holding the speakers, I replaced them with brass screws and heard a big difference--not as bright, mellower but better.
Then I replaced THOSE with titanium screws and it's the best of both worlds, not bright but clear, with tight bass and more realistic sound and imaging.
Who knew screws holding your speakers would make a difference!