Pop sound when switching on / off Pass Aleph 30?

I'm running an Anthem Pre 1L with Aleph 30 power amp. Speaker is ProAc Tablettle 50 Sig. I notice that when I turn off or on the Aleph 30, there will be a audible "pop" sound from the speakers. I wonder if this is normal else will this damage the speakers in any way?

Advice needed. Thanks.
Some power amps don't have muting circuits and when powered off it is possible for them to continue play music for a few seconds until their power supplies completely discharge. (Maybe you notice this with the Aleph 30). Amps of this design are more likely to introduce pops & clicks when turned on or off but the advantage & logic of this design is there is no sound-degrading muting relays/circuitry in the signal path.
My Aleph 30 has been doing that since I bought it. No problem.