Power strip for sequenced preamp/amp turn on and turn off?

What sounds harmful to your ears is just voltage to a speaker. If the amp can't make enough to damage the speaker with music then it can't make enough to damage it with noise either, no matter how bad it may sound.

Be that as it may, if you were able to do it religiously before then maybe switch to doing it consistently?

APC  H10  or  APC H15   will do it
But it is more than a power strip

https://www.markertek.com/product/apc-h10bk/apc-h10blk-av-1kva-h-type-power-conditioner-120v-black

Mr. Miller,
Thanks for the response, which assuages my concern.  My tube preamp and amp were made by Don Sachs and he just got back to me with his preferred solution, alleviating the potential of this noisy problem when, on very rare occasions when I reverse the power-up sequence of the preamp and power amp.

The solution is this:  Don and I both have the same commercial Powervar power conditioner.  He informs that I should connect both his preamp and power amp to the Powervar unit, leave both the preamp and amp switched on, but turn them on and off (simultaneous) with the switch on Powervar unit.    I am happily listening to music this afternoon so at the end of my listening session, I will reconnect the preamp and amp thusly.

Thanks again for your response... there are so many helpful folks on this forum.  Mark

Gents,
I reconnected my amp and preamp to my power condition with the power conditioner turned off, and then powered up them up with the switch on the power conditioner and there was a gentle startup with zero noise.  One switch handles is all with no need to reach behind the rack to get to the back of the amp in the back of my rack.  It is an elegant and simple solution.  It is Occam's Razor... 

APC  H 10 owner’s manual :
´´ Sequenced Turn On/Off
Ensures connected equipment is powered-up/down in the proper order and with the right amount of delay between the stages. This feature allows the user to program a delay into the sequence between 0 and 12 seconds. This delay feature eliminates transients that can affect connected components. ´´

That is a fine feature, thanks for the suggestion.  

@whitestix

Which specific model are you using?

This one:  https://forums.audioholics.com/forums/threads/powervar-12-amp-power-conditioner.5258/

My APC which I now just use it for video not audio because it kill dynamics on amps and subs.

@trianglezerius 
Do you use another power conditioner brand for audio ?
or is your amp  connected in the wall socket ?

@trianglezerius 
I am a bit surprised because  the two outlets , dedicated to Amps or Sub , are supposed to be  ´´ unfiltered ´´
I own both : APC H10 and APC H15 . 
May be , my ears are getting to old to  hear the difference.

I have tried the APC on every amp I have owned since getting it, Everything From a Rogues Tempest III to a Roksan Caspian MKII. It killed dynamics on  every amp so I bought a Pi Audio Groups Uberbuss which doesn't limit current.

@trianglezerius
Thanks . I will take a look at Pi Audio Groups Uberbuss. I realy appreciate.
My power amplifiers ( solid state ) and my processor are  ´´ ON ´´  24/7   , so I do not use  the ´´ delay’´ feature.

A follow up:   today hooked up a Panamax MR4300 power strip, which has RFI, EMI, and surge protection that the Uberbuss does not, and my music sounds just fine.  I can see on the front of the Panamax that my wall voltage has varied between 121V and 123V during the day, all well-tolerated by my components.  The Panamax has plugs for power components as well as line components -- 8 in all, but as a practical matter, only half of them are usable if you have upscale power cords with their large-diameter male connectors.  It works for me. 

It depends on the number of connections you need for your gear, but TLP is a reliable source for power conditioners.   I got their TF110 power conditioner, but I honestly can't say that there was any SQ improvement in the sound of my system.  The TF110 is on all the time, whereas the Panamax MR4300 has an on/off switch which is efficient:  With it, I left both my amp and preamp turned on, and with a flip of the the power switch, I used the Panamax to power up and power down my system with no spurious sound in my speakers.  
http://www.tlp-audio.com/powerConditioners2.php