Bryston 2WSB switch box to choose amp that drives speakers

This is only for switching between two sets of speakers. I have one made by Adcom. Never known of one like you describe. Are you afraid of wearing out your SS amps? Just switch by hand! The exercise will be good for you!

LOL I could use more exercise but I switch back and forth so often that it's a real pain in the arse, to the point where often I don't even bother connecting the good amp. The reason I do this is because the good amp runs in class a, so it's very hot and draws a lot of electricity, plus its a vintage Threshold that I want to limit its use for music only. I can't justify watching the news or football with it in the audio circuit. I could just use the tv's speakers for that but I also like the little amp for background music, I'll leave it on all day while coming an going. I won't do that with the Threshold. 

Good catch about the commonality of the red terminals, Treynolds155.

There are some circumstances in which that switchbox would work ok in selecting between two amplifiers if all of its red terminals are treated as black and vice versa. But I wouldn’t feel comfortable doing that with your Threshold S200. It’s manual, which I found at HiFiEngine.com, states as follows, in reference to the S200’s speaker outputs:

Each channel’s output connector consists of a red and a black post on a common base.

These outputs, should be considered as electrically isolated from the chassis and from each other. In the case of dual channel amplifiers there should be no direct interconnection between the output terminals of the two channels under normal operation. Connect the output terminals of each channel only to the loudspeaker, not to each other or to anything else.

I would infer from that that the black output terminals of your two amps, as well as their red output terminals, should not be connected together.

Other conceivable issues are the power handling capacity of the switchbox, and whether the switch is break-before-make or vice-versa. If the switch is make-before-break, when changing its setting the two amps would be connected together for a brief instant, which conceivably could be a problem if either amp is powered up at the time.

Best regards,
-- Al

Here’s a basic selector,

https://www.russound.com/products/connectivity-and-control/speaker-selectors/dual-speaker-dual-sourc...

You could also look for a Niles SAS-1 or a Niles SPK-1. These are no longer available new but can be found used. They would offer options for switching automatically.

As I posted this, I just noticed Al's post. Hopefully he will see my post and comment if my suggestions are suitable.