minimum volume for TTS?

[jmerifjKriwe]

I have an issue with TTS.

My code is:

action: media_player.play_media data: media_content_id: media-source://tts/tts.piper?message="just a test" media_content_type: music extra: volume: 0.15 target: entity_id: media_player.mainroom2

But the volume of the message is the same for 0.0 ... 0.05 ... 0.1 ... 0.15
It starts to get louder around 0.2 but seems I'm not able to get it below a certain minimum volume. That's a little bit annoying in the morning if I want to play some general information with a very low volume - because people a still someone sleeping ;-)