I am not sure if the AMP+ is the right Shield but I will explain my short Project.
My target is to build an Audio Player which plays Audio (mp3) on Raspberry Pi 2 and has the AMP+ to connect 5pcs 2.5mm Jack Connectors for Headsets (Mobilephone Headsets). The distance is 10 meters between the Raspberry and the Jack Connectors. Would the Signal be enough for that distance and multi connection?
Audio Player with Multi Connection