If you're looking for a switch that is low cost, simple to use, and does not degrade the signal quality of the analog 5.1 or 7.1 sound, here is the answer that may work for you...
This is a Philips, SWS2325W, "passive" component video switcher. I use it right now to switch my Sony SACD/DVD player and Denon Universal Player into an Outlaw Audio ICBM-1 and then on to a Denon AV Receiver. The key to this unit is that because it is "passive" (it is a manual push button box that switches internal rails for input switching instead of using IC's), it will not degrade the signal at all. In addition, even though it's really built to accommodate only six analog RCA connectors, one can still use it for 7.1 switching (see pic below) if you're willing to customize pairs of RCA cables to run through the S-Video jacks (S-Video is essentially a two channel, four wire cable).
Anyway, it appears to still be available at Amazon....
https://www.amazon.com/Philips-SWS2325W ... B001EK74WW
However, I picked up a used one on ebay for about $7. Not a bad value compared to a Zektor MAS 7.1
Hope this helps