You didn't say, but full depth, sanded-in-place, tongue-in-groove, hardwood floors are typically supported on wooden floor joists over a basement or crawl space. Wood flooring over a wood joist support system is very different from flooring over a concrete slab-on-grade. The wood joists will be more susceptible to vibrations than a floor supported over a slab-on-grade.
If your system is supported over wood joists, then an amplifier stand or support platform could be more effective than which blocks, or footers, you have directly under your amp. A platform may help spread the amplifier support over a larger area so that the support is derived directly from multiple joists while the four feet alone may be positioned on the flooring between joists. I suspect decoupling using compliant footers or springs may be more beneficial than coupling with spikes, for situations over a joist-supported wood floor. You may want to look into what has worked well for people with large speakers over joist-supported floors.
If your system is supported over wood joists, then an amplifier stand or support platform could be more effective than which blocks, or footers, you have directly under your amp. A platform may help spread the amplifier support over a larger area so that the support is derived directly from multiple joists while the four feet alone may be positioned on the flooring between joists. I suspect decoupling using compliant footers or springs may be more beneficial than coupling with spikes, for situations over a joist-supported wood floor. You may want to look into what has worked well for people with large speakers over joist-supported floors.