The only time I've really heard a difference with footers, isolation, etc, is with a turntable. In that case, get a minus K platform for your turntable. Otherwise, for other components, based on my experience, any auditory improvement will probably be minimal if any at all.
Isolation systems
I have an equipment rack that utilizes a system that has an anti-resonant material on the underside of the shelves. The rods supporting that rack are said to drain vibration from the rack into the rods and into the spiked footers. My question is, with this type of isolation system would Townshend seismic corners be beneficial or would they negate the system built into the rack. I hope this question makes sense. Trying to make improvements that would be improve on what I already have and not hinder. Thanks for any advice.