4. How to use the K7 as a USB DAC for mobile phones?

K7 does not have a battery, it is powered by a built-in linear power supply, you can purchase an OTG cable to connect to an Android phone, an iPhone or a player.
【Android phone】
K7 input setting: K7 [INPUT] switch to USB gear
K7 output setting: switch to the corresponding output port according to the interface used, switch to [PO] on the front panel headphone out, switch to [PRE] or [LO] on the rear panel line-out.
Connect the phone and K7 via USB C to USB B data cable (such as FiiO LD-TC1)
[Note] If there is no sound after you connect, you need to pay attention to the following points:
Mobile phone playback software settings, if there is a USB output setting that needs to be turned on, some devices only have sound when the USB output is turned off;
Confirm that USB debugging is enabled in the developer mode of the mobile phone;
You need to turn on USB debugging on the mobile phone, turn on "Developer Options", and then turn on the "USB debugging" or "OTG" function;
Confirm that the adapter cable supports the OTG function, and whether the direction of the cable is reversed;
Since the USB audio of various brands of mobile phones is not uniformly standardized, 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 the computer DAC to exclude whether the hardware of individual devices is faulty (such probability of the situation is small), if it can't be recognized when connect to the computer, you can consider return it to us for repairing or replacing.
You need to purchase a Lightning to USB B data cable which supports OTG function(e.g. FiiO LD-LT1) to connect K7 and iPhone/iPad/iPod, and you can enjoy high-quality music by playing songs.
Only support Apple devices with iOS10.0.2 and above. Those with lower versions cannot be supported because of the Apple system's reasons.
When the iOS device is decoding, adjusting the volume of the iOS device is invalid