Fiio R7 Manual page 51

Instructions for commonly-used functions
1.Screenshot
The R7 supports screenshot: swipe down the screen with 3 fingers.
The screenshot is stored in FiiO R7\Files\Internal
storage\Pictures\Screenshots.
2.USB Audio digital output
The R7 supports connecting to external decoders (USB Audio). Follow the
steps to enable it.
1) In FiiO Music app, turn on the USB output
2) Use an OTG adapter cable to connect the R7 to the external decoder.
3) Starting up the FiiO Music app or any music app, the R7 can work as a USB
digital device.
It supports most decoders on the market. For those unsupported, please turn
off the USB output in FiiO Music app, or unplug and re-plug the USB device
after exiting FiiO Music app to try playing again.
3.FiiO Link Bluetooth control
There are mainly 3 steps.
1) On the FiiO Music app of the R7, Settings->FiiO Link->┆ (on the upper
right corner of the display), choose Bluetooth as the Server.
2) Connect the R7 to the mobile phone through Bluetooth.
3) On the FiiO Music app of the mobile phone, Settings->FiiO Link->┆ (on the
upper right corner of the display), choose Bluetooth as the Client.
Notes: iPhones only support FiiO Link WiFi control but not Bluetooth.