This is the right comparison company to make with: HiFiMan. I have the HE-400 and love the rich sound connected to the Audio-GD Compass 2. The new headphone from Oppo better be good at least in comparison to well known brands.
Whilst I've been looking for better headhphones, DAC + amp, the cost vs. incremental increase in sound quality has me pause and think about it in more general terms.
Yes, Oppo has an excellent reputation for their universal players (I have their BDP-93), the customer service and the regular firmware up-dates to keep the unit current is a key feature that differentiates Oppo from other manufacturers.
How would Oppo allow fine tuning of the headphone to improve sound quality will be an interesting concept to be considered.