If your amps are on just play music and on the subject of crackling it can sometimes subside but not always. The crackling will not hurt your speakers in any way.
must you play music to break in tubes
I have some GE 12ax7 longplate tubes that make some loud crackling noises. The Seller claimed that this is common with nos tubes and that it will go away after they are broken in, but it is too alarming to hear and sounds risky to the speakers. Might leaving the amp powered up for a while, but with no signal passing, break them in adequately? Kind of hate wasting the power tubes lifetimes, but I don't have any old tubes to use in that amp.