Newbie Question: Bit Perfect Audio

I consider myself a borderline audiophile whereby I listen almost exclusively to high res (or 44/16) via Tidal and Qobuz and my own downloads through ripping and HD Tracks. I am really enjoying Volumio and have the PI 4 and Audiophonics Sabre 9038 Dac and it is better when comparing to running through my Onkyo Dac which was also, frankly, very good.

But what I don’t understand is what is Bit Perfect audio and in particular what is Volumio doing to make my songs sound better? What is the difference between Volumio (other than the hardware requirement) and Audirvana for instance who claim to output the best sound? Finally even if I was just doing mp3or iTunes acc it should sound better via Volumio than iTunes or other sources correct?

I found it odd that I could not find information on this on the main Volumio page or in discussions. So I would love to get feedback or a link to somewhere that explains this. Thanks.