Someone recommended an automatic 2 input optical audio switcher in one of the original playbar threads. It was from monoprice and the link is dead, and a search on monoprice makes it look like it's discontinued with nothing else up in its place.
I'm buying a new TV soon but based on what research I've done, it's impossible to be certain any TV I buy will have proper 5.1 optical switching. 99% chance it will not have it in spite of what people casually report on the internet.
So, I'll need to buy an optical audio switcher. I need to route at least three inputs, ideally four to help future proof me. And it needs to support 5.1. It does me no good if it downgrades the signal to 2.x.
I'm also debating over whether I should just buy another A/V receiver. I sold my old A/V receiver with my old 5.1 speaker set when I bought my playbar. As ridiculous as it sounds (and actually is), my best bet may be to buy a cheap $100 to $200 A/V receiver and use that for all my audio routing to the Playbar.
Then when friends come over and marvel at the slim form factor and design of the Playbar, I can point out that they'll need a gigantic A/V receiver in order to get it working properly.
I would also consider an HDMI switcher that has the appropriate audio output that parses out the correct 5.1 audio signal.
Ideally, whatever I choose, it's automatic with a manual override. I like the idea that whichever of the 4 inputs are outputting a signal is the one that is live. With the ability to manually switch for diagnostic or special use circumstances.
If that Monoprice unit comes back, even though it's just a dual unit, maybe I can get away with running two of them, one into the other, to get the 3 inputs that I need.
Or maybe someone will report that Sonos has come out with an official list of TVs that support the Playbar's intended functionality that it was engineered around (re: sending 5.1 out of optical). I haven't been on the forums in a few months and a cursory skim through thread posts didn't reveal anything new, although it sounds like Sonos may release a DTS update through software based on some rumors I read on the forums so that's exciting.