The Bowers & Wilkins PX and PX7 are both premium over-ear noise cancelling headphones. The key differences include: PX7 has improved drive units and sound quality over original PX PX7 has more advanced adaptive noise cancellation PX7 supports high-resolution audio and aptX HD PX7 uses USB-C charging while PX uses microUSB PX has analog audio option; PX7 is digital/wireless only PX7 has wear detection sensors to pause playback PX7 costs $399 retail, PX cost $349 originally