I compared the Airpods Max to Bathys and later pX8 to Bathys, I've since sold APM.
Both the PX8 & Bathys are a big step up sound wise from APM, imo. I don't think APM sound particularly good, I think Resolve's notion that technically they match a $100/£80 wired headphone is about right. Although you have an added aspect, which is the digital sound of APM. Hard to describe, you'll know when you hear it, instruments like acoustic guitar and classical ensembles just sound a bit artificial, same for vocals. Also the mid range generally on the APM sounds a bit hollow
Last night I decided to test if B&Ws flagship still deserve their P9 title. After a few weeks with PX8 I was skeptical, as i'm enjoying them so much. But yes, I do think think the P9 takes much of what the PX8 does and turns the dial to 11. You get an even bigger soundstage than Bathys, more detail than both, an incredible mid range, wonderful clear treble. The bass can be a bit too much on the wrong song, on the right song it's like nothing else. PX8 is a bit more energetic, and definately tuned to favour that on the go vibe.
P9 sound huge compared to PX8 and Bathys. For movies at least the P9 is a totally different experience, and it's my headphone of choice for film & TV, getting grabbed over Clear or Stellia for that use case. I might do a review of the P9 soon as I think it's one of the best bargains on ebay right now, at least in the UK.