Overkill in the sense that it could somehow be detrimental to sound quality or hurt your speakers? Not a chance. Overkill in the sense that you would be spending $1000's of dollars for no benefit? Definitely. <-- definitely just my opinion. Others will disagree but having A/B tested martinlogan reserve series, Bowers and wilkins 800 diamond series, sonus faber, def tech, energy, and more, I have come to conclusion that, unless your amps are at their clipping point, any benefits to higher power amps are non-existent. When it comes to volume, keep in mind that doubling power will get you 3db in volume. Discernible difference, but just barely.
For an example, I have personally AB tested the ML Montis with a denon avr x4000 vs McIntosh mx151 and mc205 amp. Cables were audioquest rocket 88 with silver spade connectors. Could not reliably discern which was which after level adjusting.
Also keep in mind a speaker does not have a resistance of 4 ohms. Resistance in a curve and your amp will see many different ohm levels. Unless your amp starts shutting down or has audible clipping, don't worry about it.