DIY amplifier/speaker switching box

FWIW, I just worked on one of the big Sansui switch boxes that you'd find at a dealer "back in the day". They use surprisingly complicated switching. When you start pushing any button, it opens a separate relay to disconnect/mute. I think it may also connect to some power resistors so the amp always sees a load. Though the speaker switching is fully floating, it appears all the negative speaker leads are common. Everything in it, in terms of switching, is custom. If I were trying to duplicate the function today, I think I'd go with relays and a PIC or something to insure the correct break before make behavior and loading while disconnected. I'm not sure about the loading as there weren't enough large power resistors for all the amps. There were some smaller ones that may have been just enough to insure stability on tube amps, maybe 50 or 100 ohms or so. Naturally there was no manual or schematic available. Regular switches make sense for a few amps, but not for ten or so!
What if I power the amps off before doing the switch? I'm not trying to A/B to amp here, only plug my speakers on my stereo receiver AND my Home theater system. Would those swith be a good option?
 
Here's what I building 2 amps one set of speakers. Putting it together now.
 

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Here's what I building 2 amps one set of speakers. Putting it together now.
As per @ConradH earlier answer, no separate relay to disconnect/mute? No power resistors connect so the amp always sees a load? Keep us posted if it's working good; I also ordered a switch so I might build another box with it if yours do the job!
 
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As per @ConradH earlier answer, no separate relay to disconnect/mute? No power resistors connect so the amp always sees a load? Keep us posted if it's working good; I also ordered a switch so I might build another box with it if yours do the job!

None of the above is required for switching between solid-state amps. A simple break-before-make switch as per my first post does the job perfectly fine.

You can leave a solid-state amp powered up all day long with no load connected and you will have no issues.

Only tube amps will have issues being powered up with no load connected.
 
None of the above is required for switching between solid-state amps. A simple break-before-make switch as per my first post does the job perfectly fine.

You can leave a solid-state amp powered up all day long with no load connected and you will have no issues.

Only tube amps will have issues being powered up with no load connected.
Good to know! Therefore I will proceed with doing my own box with the switch I ordered! :)
 
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