The normal turn on/off of system components is... amps LAST (so even powered speakers have amps so should be last on... have you tried turning everything ELSE on first, then speakers? The fact that they crackle tells me something MIGHT be coming in to cause that.. so, unplug ALL inputs to the speakers and see if the turn on sound is gone, also, trouble shooting 101 says to swap the speakers and see if the sound/problem follows the swap. If you put the speaker that makes the sound on the OTHER channel.. and the sound follows, then the problem is likely the speaker. Likewise the cables between the speaker and the source could be bad, swap cables from the speakers and see if the sound follows, if it does, the cable might be the problem...You have to think like a problem and eliminate ANY and ALL possibilities.
Now, you should also start a tech ticket in case there IS a problem with the speaker...then your in line... you can always cancel the ticket if we get you sussed here!