Allow the Audio Mixer "Fader Value" to go above 1.0

Currently the Audio Mixer Device only allows users to decrease the volume of certain sounds in their maps. I think it would be helpful if we could also increase the volume of certain sounds above the default.

The option for the Fader Value currently goes from 0.0 - 1.0, so I believe it would be helpful if it could also go up to 2.0.