7. How to use the K9 as a USB DAC for mobile phones?

The K9 does not have a battery, and is powered by a built-in linear power supply. You can purchase an OTG adapter cable to connect to an Android phone, an Apple phone or a player.

【Android phone】

1. K9 input setting: K9 [INPUT] switches to USB gear.

2. K9 output setting: switch to the corresponding output port according to the interface used, switch to [PO] on the front panel, switch to [PRE] or [LO] on the rear panel.

3. Connect the mobile phone and K9 through a type-C USB to square port data cable (such as LD-TC3) to use.

[Note] If there is no sound after you connect, you need to pay attention to the following points:

1. Mobile phone playback software settings. If there is a USB output, it needs to be turned on, and some devices have to turn off the USB output to have sound.

2. Confirm whether the mobile phone developer mode has enabled USB debugging. On the mobile phone, you need to turn on USB debugging, turn on "Developer Options", and then turn on the "USB debugging" or "OTG" function.

3. Confirm that the transfer cable supports the OTG function, and whether the direction of the cable is reversed.

4. Since the USB audio of various brands of mobile phones is not standardized at present, FiiO does not guarantee full compatibility. According to the above connection method, if it is not supported, it is recommended to try other mobile phones or connect to the computer DAC to rule out whether the hardware of some devices is bad (such the probability of the situation is small), if it is not possible to connect to the computer, consider repairing or replacing the machine.



It is necessary to purchase a Lightning to Type C data cable with OTG function (such as LD-LT1) to connect K9 and iPhone/iPad/iPod, and enjoy high-quality music by playing songs.


1. Only Apple devices with iOS10.0.2 and above systems are supported. Those with versions below this version can not be supported due to the Apple system itself.

2. When the iOS device is decoding, adjusting the volume of the iOS device is invalid.