Van Alstine. I don’t have their switchbox but it may provide what you need. Apparently there was enough demand for it they did another run of them.
Amplifier and Speaker A/B switcher
I'm looking for a well made switcher that has the ability to switch between two amps (rca cables) and two speaker pairs (using banana plugs). I am only seeing devices made in China and they don't appear to be of very good quality. Can anyone suggest a high quality device safe for my equipment and not to degrade audio quality? Thanks.