Mixer for stream and local input

Hi,

To minimize the cabling on my computer desk and being able to share my PC audio output and listening the Sonos audio stream and the PC audio output at the same time on the same speakers, the idea consists in mixing the audio input of the Sonos Zone Player and the Sonos stream when the local input in not activated.

Without this evolution, I currently use the following wiring:

PC >-+----+ . +--< Sonos stream
.. . | . .|. .|. .
. . .|. . | . | . .
.. . | . .v. .v. .
. . .|. . Sonos .
.. . | . .ZP90 .
. . .|. . . v . .
.. . | . . .|. .
. . .|. .+--+ .
.. . | . | . .
. . .v. .v. .
.. . Mixer . . . .
. . . .v. . . .
.. . . | . . . .
. . . .|. . . .
.. . . v . . .
. .Amplifier >--------> Speakers



The target is the following:

PC >----+ . +--< Sonos stream
.. . . .|. .|. .
. . . . | . | . .
.. . . .v. .v. .
. . . . Sonos . .
.. . . .ZP120. . .
. . . . . v . . . .
.. . . . .|. . . .
. . . . . | . . . .
.. . . . .v. . . .
. . Speakers


Note:
If the PC input is mixed without delay, it's better to avoid any convenience while watching video.

Advantage :
+ Less wires
+ Works when the computer is turn off
+ Avoid the audio-time-shifting during video playing on the computer
+ Reduce the noise of the external mixer and the amplifier

Drawbacks :
- Need Sonos update


Best regards.