Apple was apparently experimenting with the possibility of creating a powerful version of the Apple TV long before it created the Apple TV 4K, with the discovery of code references in the "iBoot" leak suggesting it could have used an A9X chip.
Developer Steve Troughton-Smith claims to have found references to an "A9X variant of the Apple TV that never shipped" within the leaked source code. Considering the age of the code - which was allegedly pulled from iOS 9 - the claimed unreleased device could potentially have been one of Apple's initial attempts at producing a more powerful version of its streaming set-top box.
The A9X is a 64-bit system-on-chip designed by Apple and introduced as part of the first generation of iPad Pro devices, including both the 12.9-inch and 9.7-inch models. The chip was claimed by Apple to offer double the GPU performance and 1.8 times the CPU performance of the A8X, making it the most powerful mobile processor for iOS devices at the time.
If genuine, Troughton-Smith's discovery strongly suggests Apple was looking to considerably upgrade the Apple TV's processing power, far beyond the fourth-generation device's internals, long before it had even shipped the Apple TV 4K. The hardware for the fourth generation Apple TV, launched in September 2015, centered around the A8 processor that had been used in the iPhone 6 and 6 Plus and the iPad mini 4, with the chip powerful enough to perform Siri searches and run third-party apps within tvOS.
Speaking of unreleased: there's an A9X variant of the Apple TV that never shipped, according to iBoot-- Steve Troughton-Smith (@stroughtonsmith) February 8, 2018
Apple did go on to produce a more powerful model, introducing the Apple TV 4K in September 2017 that largely kept the design and hardware considerations of the fourth-generation version. For the 4K edition, Apple ended up using the A9X's successor, the A10X Fusion, another chip used in iPad Pro models.
Surfacing earlier this week, the iBoot code is an Apple subsystem that ensures an authenticated boot, or initial loading, of iOS on a target device. It is also responsible for iOS kernel signing verification and other critical tasks, with the code leak potentially presenting an opportunity to jailbreak developers to discover new vulnerabilities.
Apple has responded to security concerns over the leak, assuring CNET the security design of its products does not rely on keeping the source code secret. "There are many layers of hardware and software protections built in to our products, and we always encourage customers to update to the newest software releases to benefit from the latest protections," Apple told the report.