That one by AVA looks like the only device that will really protect your gear. The Chinese company Douk makes exactly what you are looking for but not so sure I would trust my equipment into that thing.
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.