Personally, I don't have any problems with the sound via bluetooth, on the contrary
However, you should know how to choose a phone and headphones, both.

Have you heard of standards? Bluetooth 1.0, 2.0, 2.1 ... 4, 5, 5.2 ...Each of them has its own possibilities.
Both transmitter (phone) and receiver (headphones) must be matched.

As for the tts engine:
[Only registered and activated users can see links. ]
you can try which any you want.
Probably newer, better versions were published in the meantime