Well the "best possible sound" is both objective and highly subjective when it comes to headphones. Bob Katz' LCD4 VS Utopia article seems to be about the closest thing I've seen to an objective declaration of a tonal winner in the race for sonic purity.
Objectively and Subjectively, wireless isn't there yet. There's a chance for ORA to do it but the jury is out until product delivery.
For your preferences, I get the impression that you really value bass performance and the HD650 Will not get you there. I also remember that you have preference for mobility oriented designs. I'd recommend checking out the Audeze iSine again and giving it as much of a chance as you did with the Beats Studio. Specifically, try the Comply Comfort tips if you do. I think that's the best mobile plug and play solution for TOTL style performance. Both myself and Hawaiiboy are smitten with their bass after some EQ magic. Happy to share my Cipher bass profile with you. I think with the Comply you would have quite the different fit and sonic experience.
HTH