Question about setting up multi-zone with traditional amps

Let’s say one was opening a restaurant/bar where music and audio is a pretty important part of the experience.

And let’s say one wanted to outfit their establishment with a good audio system where there would be at least 4 stereo zones.

And let’s say that rather than using an off-the-shelf multizone amp like a Parasound, one wanted to do this with 8 efficient speakers and either 4 stereo power amps or 8 mono block power amps. 

What would the best way be to send a pre-amped signal to all those amps and the best way to control the volume of each stereo pair?

Is there such a think as a multi zone pre rather than power amp?

As an example, let’s say our bar owner decided to use 8 Zu DWX speakers and 8 Schiit Gjallarhorn amps set up as monos.

Any advice on an appropriate front end?

and then ….

Say this person realizes this is all a fools errand and decides to go thr multizone amp route … does anyone have any recommendations there?

the good thing about some of these multizone amps is a traditional preamp out signal can be sent to the bus input of the multizone amp and then applied to all the zones.