Bryston 2WSB switch box to choose amp that drives speakers

Looks perfect. Nice find!

Also, Digikey sells it for a somewhat lower price:

https://www.digikey.com/product-detail/en/honeywell-sensing-and-productivity-solutions/4NT1-1/480-21...

Best regards,
-- Al

P.S: Keep in mind that if the lower powered amp happens to be a tube amp that has output transformers, it should not be operated without a load connected to its outputs, especially if it is being provided with an input signal.

First, a couple of corrections, with respect to the Bryston switchbox:

1) Ignore my previous comments about make-before-break vs. break-before-make. I hadn’t noticed that the Bryston unit provides a separate and independent switch for each of its two signal paths.

2) Bryston’s setup diagram that is shown in one of the photos at the link provided in the OP states that it is the black binding posts that are common to all inputs and outputs, which of course directly conflicts with their schematic that is also shown.

In any event, per my other comments I would rule that device out.

I can’t tell if the Russound switchbox Tony (Tls49) linked to would be suitable, because there is no indication as to whether or not it switches both + and -. Also, if the impedance of your speakers is in the vicinity of 4 ohms your S200 amp (rated at 100 watts per channel into 8 ohms) might be a bit too powerful for it, given the 150 watt power handling spec of the switchbox.

Regarding the Niles SPK-1 both gentlemen referred to, if I understand correctly it is designed to be switched by the switched AC outlet of a Receiver or other component that it would be used with. If neither of your amps provides such an outlet that may be an issue.

Perhaps a look through all of Niles’ switchbox offerings would prove useful, if you haven’t already done so:

https://www.nilesaudio.com/products/all/speaker-selectors/all

I did take a quick look through the various pro-oriented switchers that are carried by B&H Photo Video, but everything I saw there had some combination of uncertainties, involving power ratings that would be marginal at best and/or whether or not the unit switches both + and -.

Best regards,
-- Al

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