Bug#798403: Partial fix

[JTL]

After a lot of trial and error found this work around

These commands will increment pulse audio volume up/down
Use  'pactl -- set-sink-volume <sink> +10200` to increase volume
Use  'pactl -- set-sink-volume <sink>  -10200'  to decrease volume

notice the '--' after pactl and do not use a percentage
http://osdir.com/ml/general/2012-09/msg04416.html

Then add each command to Xfce keyboard shortcuts for MM volume keys

However, that workaround should not have to be and pavucontrol worked 
just fine and all versions of Wheezy, the problem only appears in Jessie