Volume control works incorrectly when channels are not balanced

Submitted by Andrzej

Assigned to Andrzej

Link to original bug (#11800)

Description

1. Deactivate "lock channels together" in pavucontrol (output device).
2. Set Left volume to be lower than Right volume.
3. Use mouse scroll on the plugin button to control output volume.
4. Increasing volume causes volume of both channels jump back and forth.

Also, reducing volume to 0 resets the channel balance (volume of both channels will be equal once the volume is increased again).