I’m not a fan of “splitters” for multiple inputs. My opinion is that you’re better off with a rather simple RCA input switch.
Splitters often run into an impedance matching issue.
Your specific equipment’s numbers should be checked, but in general source impedance is low and input impedance is high. That lets the source pump electrons down the cables, overcoming resistance and capacitance so the downstream device gets the best possible signal.
Adding an input Y cable means you have added a second low impedance device that can draw down the signal to the point it is audibly different. That is different than a Y on an output where you are adding a second high impedance connection, much less chance of problems there.
Go with a switch for cheap, a powered mixer or selector is nicer but more expensive. I don’t recommend a passive mixer, tried one here and it is in my junk drawer. While it worked the increased volume levels I had to use to overcome the internal losses really raised the noise-floor (background hiss) to objectionable levels.
I just bit the bullet and bought 2 Ports. THey’ll be here next. I’ll just have the universal remote set so that when we trigger stereo Port 1 plays and my wife can selct what ever radio station or album from our library she wants. When we trigger “TV” on the remote, it fires up PORT which I will have set to the externaal input ….. The Inday switch is remote controlled and will choose the correct coax input depending on the selection and my wife wont have to think about the finding the line input select in the app…. A few more buck and a lot less headaches 
This because the Port input cant be controlled by the remote so I’ll just just use 2 sources into my amp through the switch. I had 2 30% upgrade credits so this is where I burned them. Thanks for your input.
So i changed my approach. Just bought a Beam 2 and hooked it up to the TV. When grouping the Beam to Port, Amp and other zones theres absolutely no buffering or stuttering. This confirms a couple of things. The audio problem was in the HDMI feed out of the PC being conberted to Optical out. It also confirms that on the S2 system the audio syncing is is way better than the S1 set up.
Now the only question i have to answer to myself is wheter i actually need 2 Ports. I think not.
I wanted to update this thread now that I've got it all sorted out and have the results I wanted
I just advantage of the Upgrade Offer from Sonos and upgraded 1 Connect and a Play 5 to a Port and a Beam Gen 2. The previous Connect I had going into my B&O system and it sounded flat and lacking dynamics until putting a DAC between the port and B&O which then sounded amazing. With the Port, I no longer need the DAC. Those AK chips need a few hours of run in but after about 50 hours the port into the B&O is lively and full of dynamics.
The system stability of S2 over S1 is night and day. There is no stuttering between grouped unit (rooms / zones) when playing local Flac off my NAS. And with the Beam 2 plugged into my TV, my audio set up is so much simpler.
Previously my Living Room audio chain looked like this:
TV > Toslink Switch ch 1 > DAC > B&O Aux In
+
Streaming + NAS Library > Connect > Toslink Switch ch 2 > DAC > B&O Aux In
With this set up I could listen to my library all over the house (with tons of drop outs / streaming was OK) but I had no way to tie in my TV into other rooms. By connecting a Beam to the TV, it now acts as in interface to the Port and it seamlessly sends the audio signal to my B&O via Port and any other room in my house. I've been able to eliminate the DAC and the switch and now I can send content anywhere around the house. I don't even listen to the Beam, except in the morning, when I listen to radio at low volume. And it actually sounds pretty good, but it's the perfect connector into the rest of the ecosystem. My whole system boots up quicker and switching sources is a breeze. I couldn't be happier.
Is it hi rez? No. Do I care? No. I've got a Bryson set up in another room for critical listening but as for the rest of the house Sonos in the backyard, garage, Bathroom 1, Bathroom 2, Living Room, My Office, Wife Office and everything perfectly sync'd & sounding sweet.
