How to Control Volume Changes in Smaller Steps and in Lower Region? I have new wireless Bluetooth headset but I find that the volume control there is not sufficient with the current steps (much less volume is needed there). I would also like to have finer control of the volume band. 
There appeared the sound control of Bluetooth device but it is not sufficient in the top bar as a scrollbar

Hardware: Oneplus 2
OS: CyanogenMod 13
Client: Spotify
Output client: Wireless 4.1 Bluetooth headset
Not possible at the moment in Android 6 - 7. 

Proposal: External USB dongle with the phone. + Adaptive control with external sound exclusions.