The Px8 have been so good they’ve made me upgrade my existing B&W speakers and also add another set to the house.
I recently got a Bluesound Node for streaming for one of the systems and it also gave me a chance to try out the Px8 in AptX HD.
The difference to my ears between AAC and AptX HD is noticeable, a good 10% improvement at least. There’s a bit more spaciousness and everything is a bit tightened up and clarity dialed up ever so slightly. Ideally I would be listening to them like this, but even in AAC with my Apple devices I am more than happy. I would not walk around with dongles out of my iOS devices for it or get a dedicated player, nor am I switching away from my iPhone.