Sound
The sound adds a fourth dimension to the flightdeck. In the above picture you can see the two small amplifiers for the flight deck Channel 2 & channel 3. Inexpensive but adds a nice element.
Channel 1
This left & right sound channel is driven off of the P3D Server and only plays engine sounds.
Channel 2
My Instructor station drives sounds to the speakers above the captain and first officer. This left & right sound channel only plays call out sounds. Warnings, GPWS, etc.
Channel 3
My Captain Server drives sounds to the speakers install in the back wall above the circuit breakers. This left & right sound channel only play cabin calls. These cabin cables are included in the Sim-Avionics sound package and add a flight crew element to the sound experience. Very cool.