AC Power Between Amp and Preamp

Just a 2-cent suggestion:
Why don't you experiment? Leave out the surge protector and power up your amp and sub apart from your pre and listen to some music with lots of dynamics in it. If you hear a pleasing difference in the music, try the same, powering ALL your units through the protector. If the sound doesn't change, fine. The protector obviously does no harm. Now plug it all back in as you usually do it. If you don't hear any real change from before, why worry. Leave it as is.
Actually though, powering your units the way that you do is supposed to be one of the biggest mortal sins in Audiophila. However, we all are sinners and there are always exceptions to the rule. (:

Switching the many amps drawn by the power amp will shorten the life of the switch in the preamp. Why not get a heav duty relay from Radio Shack and let it do the switching. You can get a relay where the coil (control) is 115 volts. Install the relay in an electrical box with an outlet turned on by the relay.

I had a CJ preamp with outlets, one switched the others always on. Not only did equipment sound better when it was not plugged into it but the preamp sounded better when those outlets were disconnected internally.

ET

I did switch the power set-up to bypass the pre-amp and actually got a hum! Switched it back and was fine.

I'd be very surprised if there would be a noticable increase in sound quality by powering the amp differently. I am more concerned about too much voltage running through the Pre.

I did in fact dig out the SP-12 Pre-amp manual I've had since 1985 and it does specifically refer to plugging the amp into the switched outlet on the back of the Pre-amp.

The SP-12 has two power switches. The instructions state to use the 1st switch on the Pre to power just the Pre, wait a minute for it to warm and then press the second power button which then activates the switched outlet on the back and allows the amp to power-up.

Of course after all these years I hardly wait a minute between depressing the two switches and click the second switch right after the first.

As I said, I haven't run into any issues and very pleased with the sound so I guess it works fine as is. Maybe I'll be more diligent in letting the Pre warm a bit before powering the amp.

All in all, (depending upon your equipment and the Amps they draw) in most instances you would be much better off plugging your Amp into a seperate outlet instead of into the Preamp.
Pardon the question, but I have to ask, how hard is it to turn on 2 devices instead of one ?

I have an old and inexpensive Adcom ACE-515 AC Enhancer. It isn't anything fancy, and Adcom now sells an improved model. However, it does claim to do some filtering and spike/surge protection, but for me the best feature is that it properly sequences power up and power down of the source components and the power amps.