Since Sonos launched its S2 app midway through 2020, it empowered many of its old and new wireless speakers with the ability to play lossless-quality audio.
Specifically, the update enabled Sonos speakers to play audio up to 24-bit/48 kHz, which is much better than MP3-quality audio and even better than standard CD-quality audio (16-bit/44.1 kHz).
That said, not every Sonos speaker owner can play the same quality of lossless audio tracks — it matters which lossless streaming service you subscribe and, to a lesser extent, which Sonos speakers you have.

Your streaming service matters
Other than Spotify and Pandora, most music streaming services nowadays support lossless-quality audio tracks. So, if you’re a paying service member and have the proper speakers and hi-fi setup, you can listen to them.
However, different music services support different levels of lossless audio. And, more importantly to Sonos speaker owners, Sonos only supports the max audio quality of up to 24-bit/48 kHz for a few streaming services … and they aren’t necessarily the ones you expect.