Fix desktop default volume

[bzh-bzh]

i just had my ears blasted out

It's supposed to be adjusted here, but volume is still set to max upon login.

[cg505]

While we're at it, I manually put something in my .desktoprc to switch the audio output on eruption to the USB thing on top of the desk. It might be nice to do that automatically as well. (this is not as important, though)