How to stream analog audio multi room/multi zone

Thank you for the Info. And yes, I know that that the Up2stream can basically do all of that stuff too, but its inconsistant in its user Interface and very complicated, and only accessible from your App.
The Music Player Deamon (mpd) on the Raspberry (the base for the Web Radio) is much more flexible in its configuration and Usage. It has clients on everything that has a processor, and those Clients (mpc - mp Control) are easy to use.
I added a 4 Wire I2C interfaced 4x20 LCD Display to the Raspi GPIO (could as well be a TFT, Touch Display, OLED-you name it) to Display Station Name, Song Name Played, Date-Time-Status, Ip Adress/Status of Server (of the Raspi that is) , mpd Status, even a Line (via a Menue Button) that displays RSS Messages from the Station (News weather, whatever). I put some Next/Previous Chanel , Vol up/Down , Mute, Menue, Shutdown Buttons, switch to Bluetooth(Send and Receive)/Shairport Service on the RasPi connected to the GPIO (6 Alltogether-Some (female) Members of my household are, ahem, not too fancy about electronics and Smartphones, they want Physical information/usage). I personaly would have favored an OLED Display/Touch Screen, but the female members prefered a bigger, better visible 4x20 LCD backlited. So it will be!
And we even programmed a Web Interface with Apache. that lets you control everything by builtin mpd features, even makes a Library (SQL Database;with automated artworks downoiad) of every Music Album it finds in the NAS Music Directory -and much much more.
Sorry, but with the only over the Smartphone usable 4Stream App - nocando.
And everything is done by a Raspberry Zero-That even works with Touch interface and desktop Version of Raspian to do all of the above-even though this is coming to the limits of the RPI Zero.
So what do I have? A Webradio, easily controled by various Platforms (Buttons, Display, Webinterface, MPC Clients) done by: Raspberry Zero WH, 6 Buttons, and a 4x20 LCD and an Up2stream amp V4 ! (Naturely Speakers also).
And without using a touchscreen, it works as well good on an old Raspi 2B - all using the DAC of the Up2Stream.
I know that the Operating System of the up2Stream must be a Linux Base, so it should not be hard to Integrate an configurable (ip, Port, User , PW) mpc Control.
That and VLC are the Base for 99% of all Music on Raspberry!
The Basis of all that Configuration was done by Bob Rathbone, not by me
www.bobrathbone.com
I just extended it!