Hi Petter and thanks for reporting this bug!
The problem is inconsistent naming of volume controls - on some machines, such as yours, the "Front" volume control is part of what's controlling the headphone volume, but on most machines, it isn't. So PulseAudio can't know - based on the name - whether to use the "front" volume control or turn it off. Current behaviour is to turn it off, but I've been thinking about whether setting it to zero would be better.
In your case you actually have a "virtual" master control so you would get the same sound quality as if you were able to control "Front".
Hi Petter and thanks for reporting this bug!
The problem is inconsistent naming of volume controls - on some machines, such as yours, the "Front" volume control is part of what's controlling the headphone volume, but on most machines, it isn't. So PulseAudio can't know - based on the name - whether to use the "front" volume control or turn it off. Current behaviour is to turn it off, but I've been thinking about whether setting it to zero would be better.
In your case you actually have a "virtual" master control so you would get the same sound quality as if you were able to control "Front".