I've experienced significant improvement through the use of resonance control – equipment feet and amp stands!
Years back I put my Threshold SA-4e on a Sicomin plate. That was a big step ahead - cleaner sound, improved bass and dynamics. Later I bought a Copulare stand (www.copulare.com) and reached a significant higher level of improvement for the SA-4e and the Krell FPB 300 which replaced the Threshold.
Today I have a wonderful Chord SPM 5000 power amp. Although I already use the Copulare Aural amp stand I got further improvement replacing the standard equipment feet with Millennium Audio M-Pucks. Later I ordered a special integrated resonance control for this amp, called Chord Integra System instead of the M-pucks. Again another level of improvement. I tried to use the excellent Integra System to place the Chord directly on the floor, without the Copulare stand. It was immediately obvious that the crystal clear sound suffered. So I placed the Chord with the Integra System on my Copulare stand. The combination of both methods of resonance control gives best results.
So – yes, excellent resonance control will definitely improve your amps performance. I think the amps suffer from vibrations that they primarily produce themselves and secondarily pick from the environment. My amps are solid state and the Chord even uses light weight switching power supplys. Nevertheless they all are as sensitive as you would expect from tube gear.