System simplification ideas ...

[Snoopy8]

There is still the 60 ms latency in the Reactors. How will you compensate for that with TV and KTV?

For the KTV setup currently I have a delay between the TV sound and the speaker (after passing by the mixer).
Solution is to mute the TV sound and just use the mixer output sound.
The same should works with the new setup?

Good that you have considered the latency.  

Maybe you should consider buying a 8 port HDMI switch to replace the the 3 port switch.  HDMI handshaking can sometimes be temperamental and you may have less problems with a single switch?

What are you using to convert HDMI to optical?  I use one of these:

https://www.bhphotovideo.com/c/product/9...th_3d.html