Micro amplifier

I wish to create a small amplifier which allows the following input sources: - 4 x 3.5mm audio. (input 1), (input 2), (input 3), (input 4). - 1 x 2.5mm audio (input 5) - 1 x microphone - 1 x push-to-talk/volume/answer/hang up switch There should be one output which is a 3.5mm jack. Each input should be prioritised as follows: 1. input 1 2. input 5 3. Input 2 4. Input 3 5. Input 4 The push to talk switch, and microphone should feed through to input 1, and input 5. The use of this device will allow a user to have multiple devices into their amplifier, for example a phone, a walkytalky, sat nav, ipod etc. It use should be powered by a minimal voltage. I am looking for an example board to be created for testing. Further development will be to create a smaller model as possible, as use is designed for a motorbike.