@noromance That unit looks easier, but it says 8 channel. is that enough for three speaker pairs?Since noromance did not respond to your question, maybe I can give you some suggestions.
If you don’t mind using a remote control instead of WiFi, and switching left and right channel separately, here is the wiring diagram (second photo of my system page):
https://ucarecdn.audiogon.com/a5cd4597-d2ed-40d9-8778-1e5d5082566b/-/autorotate/yes/
Since the speakers negative terminal are tied together, 6 relay channel is enough for 3 speaker pairs, the down side is it’s not advisable to use as a amplifier switcher( I think you won’t mind anyway).
The diagram only show one channel, the other channel should wired the same. Please note that ONLY one pair of speaker will be powered even ALL speakers are turn on, this is to prevent overloading the amplifier.
Those connectors all look way too small to handle 14 gauge. I currently use tinned braided monster cable.I suggest use 16 or 18 gauge solid cable connect the relay to speaker binding post instead of stranded cable to avoid short circuit!
Is sound not degraded running through these selector units?I don’t think this relay base selector degrade sound quality more than the ADCOM GFS-3, and because such a small length of wire, you don’t have to worry using 16/18 gauge connecting the relay to binding post. BTW, just imagine how thick is the speaker driver voice coil wire?