SP - 10 channel switch

mcby,

Sorry, Yes, really busy these days....

For the switch you can buy a cheap one (several dollar) or good one (about $3xx) or use reply module (abour $200)

It is simple switch the signal in to volume.

Need to confirm which one you will use before we can explain more in details.

Yes, good switch is better than relay, most high-end products use physical switch instead of relay

You can connect 4 pairs of RCA to the switch (input) and there is 1 output from the switch.

Different switch connection is different, you better ask the vendor for the details.