Tried them wired with 3.5mm to my FiiO X1 and they sound very well, and respond very well to the FiiO equaliser.
Then I plugged the 3.5mm also in the Plantronics BackBeat Pro... No chance, they definitely sound much much better than the H9, even for how much I love the H9. Highs are stellar on both, but the PLT BBP have those sharp basses... Mixed with those sparkling trebles... I will definitely miss them.
H9 are just a little microscopic tiny bit warmer than the BBP. But the BBP signature really for me is something to die for.
Also another unpleasant notice about the H9: they do work when connected to my Pixel 3 via USB-C, but the audio volume is unbearably low. Like half than it is with Bluetooth, or one third of how it is when USB-C'd to the laptop.
I'm 99% sure it's an Android issue though.