The MAS head station comprises up to 8 sound sources and distributes them onto 4 main lines that can accommodate up to 25 seat modules each.

Coach MAS / Multi-channel Audio System
MAS head station
The head station for the Multi-channel Audio System individually supplies the seats in the coach with sound from such sources as radio, cassette, CD, CD changer and video.
In the head station, 8 sound sources are bundled into a multiplex signal and distributed to four main lines
Each of these 4 main lines can accommodate up to a maximum of 25 seat modules
Microphone announcements have priority on all programmes.