What is the type of your power amp, solid state or tube amp. Solid state power amp will more easy to have "pop" sound, you can check that power amp have speaker protector or not OR consider install a output delay in your pre amp. No matter how you should turn on power amp after turn on pre amp, and should shut down power amp before turn off pre amp.
So normally the procedure should be:
Turn on CD player --- Turn on pre amp --- (wait 30 to 60 sec) Turn on power amp
Shut down power amp --- (unit no sound come out from speaker)Shut down pre amp --- shut down CD player
