Nabu casa TTS low volume

I have started using the Nabu casa TTS and it works great.
But It’s quite low volume compared to Google assistant normal volume.

I have in some automations used the method to turn on, get current volume, set a higher volume, speak the message, then lower the volume again.
It works fine. But perhaps a better solution would be a “gain control” so that you can set it higher or lower to match the speakers other sounds.

Would this be possible to implement?