Different systems playing same music simultaneously

You can do this through Roon.

Bluesound is probably what you want. 
A set of Nodes- and they don't have to be the latest edition, will give you what you want as a very competitive price.
It is what I am using as I write...
Bob

Depend on setup.
If all analog signals means running lots of long runs of cables and a multi out box, can be done but it's work.
Networking as Audiotroy states is better option.
But all depends what you have in your systems.

Guys we sell the Blue Sound products which are fantastic, however, only Roon gives you the ability to talk to many different devices,  so through Roon you can talk to Sonos, Google Chromecasts, Naim Muso, Naim  Uniti products, Auralic, and many, many others.

Blue Sound's Node is a very good $550 streamer, however, a high end Roon server coupled to a good Dac will sound even better.


Dave and Troy
Audio Doctor NJ

I am using a Dayton Audio wave link 2.4 GHz wireless transmitter/receiver to send signals from my music room to a second system in my kitchen.  Bought from Parts Express.  Cost about $60.00.  Works great but there are certain limitations.  You'll need an output from the preamp and assuming you are sending an output to your amp you'll need a second pre output.  Tape out could work or maybe headphone out.  Transmitter and receiver work best with line of sight between the two.  Call Parts Express with your questions.  

Rayd