· None of the above quite fits
· App interface looks or behaves oddly
· When AirPods Max are connected via usb-c to iPad or iPhone, Roon signal path reports it as Bluetooth
· Orbi 6e mesh.
Unfortunately, you have to turn off Bluetooth in order for Roon to recognize the AirPods Max as “headphones” and definitively use the USB-C path. There has been some discussion about this topic elsewhere, including whether Apple has provided the needed API switchgear for apps outside its own Music ecosystem.
I did a bit more digging into this using a small Swift Playgrounds app querying AVAudioSession.currentRoute, and the behaviour seems more complicated than just “Roon misidentifies USB-C AirPods Max”.
With Bluetooth enabled and USB-C connected, iOS exposes the route to third-party apps as:
Type: BluetoothA2DPOutput
via:
AVAudioSession.sharedInstance().currentRoute.outputs
So in that state, Roon is actually reporting what the public API is giving it.
Interestingly though, Control Center simultaneously labels the connection as “USB Audio”, so internally iOS clearly knows there is a USB audio path active.
When I disable Bluetooth completely (while leaving USB-C connected), the route changes entirely. The same API then reports:
Name: AirPods Max USB Audio
Type: Headphones UID: AppleUSBAudioEngine:Apple Inc.:AirPods Max USB Audio…
At that point:
That makes me think there are actually two distinct operating modes here, not just a cosmetic reporting issue.
My current theory is:
So I’m not sure it’s accurate to say “Bluetooth must be off for Roon to definitively use USB-C”. What seems more accurate is:
Roon appears to just reflect whichever route abstraction iOS exposes through AVAudioSession.
The unresolved part is whether the Bluetooth-enabled mode is:
The cleanest way to answer that would probably be on a Mac using Apple Bluetooth developer tools (PacketLogger/Bluetooth Explorer). Someone could check whether active A2DP audio packets are still flowing while USB-C audio is playing. If only BLE/control traffic is present, then it would suggest audio is actually travelling over USB even though iOS reports the route as Bluetooth.
Hello
Your findings with AVAudioSession explain exactly why Roon reports what it reports. It’s a classic case of the OS abstraction layer throwing third-party developers under the bus.
According to everything Apple states online, the USB-C AirPods Max should natively support Lossless audio (up to 24-bit/48kHz) over a wired connection. However, there is a huge catch that everyone always forgets: Apple’s internal DSP.
Even when connected via USB-C, the audio signal doesn’t just go straight to the drivers. It passes through Apple’s proprietary H-series chip stack for real-time DSP, Adaptive EQ, ANC, and spatial processing.
Because Apple’s audio pipeline and APIs are completely closed, it is a total black box.
There is absolutely no public API that allows third-party apps like Roon to look “under the hood” of the chip and see whether iOS is actually passing pristine PCM or sneakily re-encoding it to AAC when Bluetooth is active. Roon can only reflect the abstraction layer AVAudioSession provides.
Ultimately, this isn’t a Roon issue - it’s entirely on Apple’s implementation. Whether it’s a cosmetic API quirk or actual background compression is a question only Apple’s CoreAudio engineers can answer.
Thanks for your understanding.