[Google Pixel 2 XL Guides, News, & Discussion] holtmann:
Apple USB-C to 3.5mm adapter

Out of curiosity I got the USB-C to 3.5mm headphone adapter from Apple (meant for the new iPad Pro). Plugged into an Android device (I tested on a Mi5s) it's recognised as an USB audio device.

Here are some first results:

1) Playing music using Spotify (Android Audio) the sounds is clean, but volume levels are extremely low. Much lower than the Google USB C to 3.5mm adapter or any other adapter I've tested. I tested with low impedance headphones.

2) Playing music using a dedicated USB Audio App (I used USB Audio Player and Neutron) there is only digital noise.

I assume it's working with normal volume levels on an iPad Pro (I don't own one) and in Android maximum audio levels are low due to mixer/digital gain settings.

Here is the USB device info for the adapter in case anyone is interested:

Device Info

Device Path: /dev/bus/usb/001/004

Device Class: Miscellaneous (0xef)

Vendor ID: 05ac

Vendor Name (reported): Apple, Inc.

Vendor Name (from DB): Apple, Inc.

Product ID: 110a

Product Name (reported): USB-C to 3.5mm Headphone Jack Adapter

Product Name (from DB): not found

Additional Info

Interface #0

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x81 (10000001)

Number : 1

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 6

Attributes : 000000011

Interface #1

Class: Audio Device (0x1)

Endpoints: none

Interface #2

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x02 (000000010)

Number : 2

Direction : Outbound (0x0)

Type : Isochronous (0x1)

Poll Interval : 1

Max Packet Size: 288

Attributes : 00000001101

Interface #3

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x02 (000000010)

Number : 2

Direction : Outbound (0x0)

Type : Isochronous (0x1)

Poll Interval : 1

Max Packet Size: 192

Attributes : 00000001101

Interface #4

Class: Human Interaction Device (0x3)

Endpoint: #0

Address : 0x85 (10000101)

Number : 5

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 64

Attributes : 000000011

Interface #5

Class: Human Interaction Device (0x3)

Endpoint: #0

Address : 0x86 (10000110)

Number : 6

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 64

Attributes : 000000011

Interface #6

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x81 (10000001)

Number : 1

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 6

Attributes : 000000011

Interface #7

Class: Audio Device (0x1)

Endpoints: none

Interface #8

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x02 (000000010)

Number : 2

Direction : Outbound (0x0)

Type : Isochronous (0x1)

Poll Interval : 1

Max Packet Size: 288

Attributes : 00000001101

Interface #9

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x02 (000000010)

Number : 2

Direction : Outbound (0x0)

Type : Isochronous (0x1)

Poll Interval : 1

Max Packet Size: 192

Attributes : 00000001101

Interface #10

Class: Human Interaction Device (0x3)

Endpoint: #0

Address : 0x85 (10000101)

Number : 5

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 64

Attributes : 000000011

Interface #11

Class: Human Interaction Device (0x3)

Endpoint: #0

Address : 0x86 (10000110)

Number : 6

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 64

Attributes : 000000011

Interface #12

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x81 (10000001)

Number : 1

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 6

Attributes : 000000011

Interface #13

Class: Audio Device (0x1)

Endpoints: none

Interface #14

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x02 (000000010)

Number : 2

Direction : Outbound (0x0)

Type : Isochronous (0x1)

Poll Interval : 1

Max Packet Size: 288

Attributes : 00000001101

Interface #15

Class: Audio Device (0x1)

Endpoint: #0

Address : 0x02 (000000010)

Number : 2

Direction : Outbound (0x0)

Type : Isochronous (0x1)

Poll Interval : 1

Max Packet Size: 192

Attributes : 00000001101

Interface #16

Class: Human Interaction Device (0x3)

Endpoint: #0

Address : 0x85 (10000101)

Number : 5

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 64

Attributes : 000000011

Interface #17

Class: Human Interaction Device (0x3)

Endpoint: #0

Address : 0x86 (10000110)

Number : 6

Direction : Inbound (0x80)

Type : Intrrupt (0x3)

Poll Interval : 1

Max Packet Size: 64

Attributes : 000000011