Power up your amp last. This should minimize any spike to your speakers. Also, if you have a ceiling fan in your room, you might get a pretty good spike if you shut it off while your gear is powered up...if it is on the same circuit.

Better yet, with solid state, leave it on. It doesn't draw much current at idle and it will keep the system cooked. I've had my gear turned on for "years" with very little time turned off. Of course, always turn off your gear when you are messing around with interconnects and cables...you can get a really nice "pop" if you don't. Yes, I have forgot a time or two.