Speaker make "pop" noise when pre amp turn off

Does anyone have any idea what cause the speakers to make a "poping" sound when the pre amp is turn off?
Any remedies to this? It sounds fine when all the componet are on. The system does not have a hum problem. This only happen when the pre amp is turn off, or the amp turn off with the pre amp off?
Anyone has any idea?
The correct sequence is...
ON: first - set preamp volume to minimum or muted
second - turn on preamp
third - turn on amp
OFF: first - set preamp volume to minimum or muted
second - turn off amp
third - turn off preamp
Blueswan hit it on the head. Do this and you should not have any problems.
Alternative sequence:
set preamp volume to minimum when not listening, but always leave it ON. That's what I do.
Is there any ARC REFII MKI owner experiencing the "pop" problem from speakers while switching to mute with power amp remaining on? Is that normal or something is going wrong? The preamp is working just fine while playing the music. My power amp is Pass X-600. Thanks in advance.
Strange. I own an ARC Ref2 MkII but I only hear the 'pop' on the left channel when I turn off the preamp while the amp is on. Not a sound when switching to mute on the preamp. To avoid any kind of pop, I either use the mute switch on my Rowland 8T amp or put the amp on standby mode before switching off the preamp.
Gtan: Thanks for your comments. Yes, I am currently using the standby switch of my power amp to avoid having the 'pop' from preamp. Maybe I should ask ARC's support/customer service about my case. BTW, I don't have the problem of turning off the preamp while power amp is on.
The pop could be from preamp or power amp. The cause could be the mismatched of aging tubes/transistors, leakage capacitor, or poor grounding. When I have ARC's LS5/VT100 MKII, I can switch anything off without a pop. Let a good technician check it.
Thanks for all for responding. Problem is not noticable any longer after performing the steps decsribed above.