Hello Vasr,
OK, now I understand that you would like to have some switching/distribution mechanism in speaker level signals after the amplifiers.
In Hi-Fi level sound quality scene, you need to be very careful to avoid any degradation in speaker level.
Recently, I also intensively tried and experienced this kind of switching/distribution in speaker level signals in
my multichannel project where I need to switch "single-amp system" and "multi-amp system" with one common speaker system.
After my intensive try-and-error on this issue, my current "physical" solution is a very primitive "SP Cabling Board";
View attachment 75324
As wrote in the above image, I once tested "Multiple-Terminal Electromagnetic Switching Relay" with remote controller and also "Multi-Terminal Snap-Toggle Switch" to switch the SP cabling connections. Both of them worked physically and functionally perfect; I found, however, audible slight degradation in sound quality was caused by these "Relay" and "Toggle Switch".
Then, I finally reached my definitive conclusion that the "physical screw-up of the cables" on terminal block is the best solution with completely no degradation of the signals in Hi-Fi system.
After reaching this conclusion, I searched and investigated a lot about the reasons for the degradation of the signals by those electromagnetic relays and toggle switches, and I found that these relays and switches have rather strong eletromagnets and/or permanent magnets in it, even toggle switches have tiny permanent magnet to "divert" possible ark spark from the contact metal plates, and these tiny but strong magnets are mal-affecting if the SP level audio signals would be switched by them.
I believe you may have, more or less, this kind of magnetic mal-affection on your SP level signals even using any of "consumer or professional audio switching gears" for SP level signals.
I am sorry that at present I cannot suggest best solution for your demands, but in Hi-Fi level audio, the switching of SP level signal should be handled very carefully, otherwise you would have audible degradation of the signal.
My present suggestion is that you should avoid any switching in SP level signals in your system, and you would be better to re-consider to have digital switching mechanism before the signals go into the DACs.
I found (and
Pavel of OCTO confirmed) that you can achieve two DAC8PROs in sync manner by connecting first DAC8PRO's AES/EBU digital OUT (CH1+CH2) into second DAC8PRO's AES/EBU digital IN, and both DACs still can work as 8 channel USB DAC, and you would have 16 channel DAC port available for flexible output routing for 16 channel amplifiers. I assume this 16 channel DAC operation could be another possible solution for you.