Spatial audio uses built-in gyroscopes and accelerometers to track movement of the user's head and provide what Apple describes as a "theater-like" experience.

The Lightning port can also be used for line-in audio, with Apple selling cables with USB-A, USB-C and 3.5mm headphone ends.

The AirPods Max Smart Case's design has been mocked by technology reviewers, along with users on Twitter for its resemblance to that of a bra or purse.

Reporter Daniel Piper of Creative Bloq states: "If we're not entirely convinced by the design of the AirPods Max themselves, we're utterly baffled by that of their charging 'Smart Case'.

"[19][20][21] Numerous people have reported that condensation can build up near the drivers of the closed-back headphones after prolonged use under the removable ear cups.