To the original poster's question. A 2019 A8 should have the capability to stream from your phone, play through SD card, USB direct or through Android Auto or Car Play.
There is a good overview of the whole system here
https://www.google.co.uk/amp/s/www.pocket-lint.com/cars/news/audi/140154-audi-mmi-infotainment-tech-review-explored-cars.amphtml
None of them will make the speakers / sound quality any better....