I have a pair of Bluetooth headphones that only control the volume on the headset and not the sending device.
On my Phone I can set the volume independently to the volume on the headset.
On the F5+ however the volume setting seems to make no difference.
The reason this is an issue is that as I use my headphones on both my phone and F5+ and have sending volume set on my phone so that the headphones don't distort. So being able to set the F5+ volume to the same level as the phone would ensure switching devices would play at the same volume