Remember. Sony implemented the LDAC "standard" with the last player generation. It worked very fine for me with my 1000X headphones. Currently, I'm looking for a player update (balance / better EQ / good battery time etc.pp) with LDAC support and the 300 looks very nice and the gimmicks are great.... BUT a 700 Euro player without any controlling the sound characteristics while using BT is a show-stopper! Now, the LDAC connectivity is just a commercial gimmick without any relevance for the latest player generation. Sorry. This is absolutely absurd.
In my mind, the 300 will never support the BT sound chars.... but it's just my opinion... I'm very unhappy.
btw. I remember the FW releases of the 100.... two years later and my 100 stuck very often while connection my LDAC headphones.... I fwd this problem last year... but without any comment / success / FW update of Sony.