With all the talk of home automation and network control in today's world there must be some company that manufactures a networked controlled speaker selector.
Here is what I would like to see.(this is audio only)
1- must be able to connect on home network (gigabit preferred--hard
Wired and wirelessly)
2- multi speaker support (4-8)- impedance matching transformer
2a- 2 channel inputs would be nice
3- each channel has volume control
4- controlled by app. Android/iOS
5- app control over selector, volume, on/off per channel

Question- does any one manufacture this product and where to purchases?

Hmmm, RTI app, processor, amp and speakers. Sounds like a complete system to me. Am I not understanding the question? Or you just wantbto run one pair of speakers so a multi channel amp is too much. Then Nuvo, Sonos amd others.

That product doesn't make any sense to me.
With all that, you are talking about a multi-room audio system. That there are dozens & dozens of brands out there already.
Or do you think such a product can be made for pennies and come in at a fraction of the cost of a multi-room audio system. Answer: NO!

Aussie51,

I'm not aware of any such current product and this does not make much sense in the current environment. Now, we have network appliances that offer these features (and more), but there is a dedicated amplifier per pair of speakers. Since there would not be much call for your speaker selector product, its cost would be high, similar to the cost of the much more flexible multi-amplifier products. A great feature of the multi-amplifier approach is that each amplifier can supply a different program.

If you dig around you may be able to find used or forgotten Xantech RAT1's. Be sure to pay attention to the details and keep track of costs because the RAT1's need a supporting cast of characters.

While there would be a lot of construction details, it would not be very hard to throw together a relay based Raspberry Pi project.