MEDION X14339: How to turn off the screen while playing audio only?

[XPloRR]

I have a MEDION X14339 (MD30059) Android TV.
When I listen to an audio only source (via tv or app) I want to turn the screen off.
I can do that manually via: Settings/Device-preferences/Power/Picture Off
Question: how can I do this automatically via the screen saver function after 5 minutes?
There is a screen saver function, but if I select "Turn Screen Off" the TV goes to sleep completely and the audio is stopped.
Is there any other option?
Ps. the Kodi app also has a power saving option to turn off the screen after a selected time, but the backlight always keeps on while the screen is blank.
So I really need a hardware screen off function like in Settings/Device-preferences/Power/Picture Off.
If not, is there an easier way via the remote via a 1 button click to do the same as Settings/Device-preferences/Power/Picture Off?
If not: can this be implemented as a new feature in the screen saver in the next firmware upgrade?