I would suspect that a short period of high volume would be more likely to damage a speaker than the amplifier.
So, the first thing to do, if you've not already done so, is to ascertain if the damage is in the receiver's right channel, or in the right main speaker. Switch the connections to your speakers so that the left main is being driven by the right channel of your receiver. If the crackling is still in the right hand speaker, i.e., the one now being driven by the left hand channel of your receiver, then the excess volume damaged the speaker and not the receiver. If this is the case, the new M60s will certainly solve the problem.
However, if the crackling is now in your left main speaker, i.e., the speaker being driven by the right channel of your receiver, then the problem is indeed in your receiver. Problem is, we can't know if the damage is in the preamplifier section of the right channel, which would necessitate a new receiver (or separates), or in the right channel amplifier section, which would permit using your current receiver as a preamplifier to another amplifier. The only way to be certain would be to hook up your receiver, as a preamp, to a separate amplifier to see if you still get the crackling.
"People generally quarrel because they cannot argue." - G. K. Chesterton