Questyle M18i Mobile Headphone Amplifier with DAC User Manual
M18i Description of keys and interfaces
M18i Audio Input and output connection
Source Input mode switching operation instructions
Smartphone Mode
– Put the Mode Switch to “Smartphone Mode”， OLED displays the current source mode 
accordingly.
– Connect the Smartphones to M18i USB Audio input port via L-C cable or C-C cable；
– Play music on the smartphones，OLED displays corresponding audio formats and sample rates。
PC Mode
– Put the Mode Switch to “PC Mode”， OLED displays the current source mode accordingly.
– Connect the PCs/tablets to M18i USB audio input port via C-C cable (The unit is equipped with Type-C to Type-C OTG data cable and USB2.0 Type-A to Type-C adapter.。
– Play music on the PCs/tablets，OLED displays corresponding audio formats and sample rates。
Bluetooth Mode
– Put the Mode Switch to “Bluetooth Mode”， OLED displays the current Bluetooth mode accordingly.
– When switch to Bluetooth mode for the first time，M18i will enter pairing mode automatically. OLED displays the pairing status accordingly，
– Search and Select“M18i”on the Setup menu of Bluetooth source devices(eg mobile phones/PCs/tablets) to connect . After connect successfully, the OLED shows the paired icon.
– Play music on the Bluetooth source devices，OLED displays corresponding audio formats and sample rates.
– During Bluetooth playback status, single press key“MFB”to Pause and Play the music. OLED displays corresponding status。
– During Bluetooth playback status，Double press key“MFB”to jump to Next track。
– When call is incomming, single press “MFB” to answer, and double press“MFB”to hang up.
– During the phone calling and outgoing calling, single press “MFB”to hang up.
Remark：When disconnect the Bluetooth, OLED disaplys “Disconnect icon”.
Long press key“MFB ”2s to enter bluetooth pairig mode again.
Volume Adjustment
– Single press “VOL -”to decrease the volume level by 1 step,Press and hold“VOL -” decrease the volume level continuously；
– Single press “VOL +”to increase the volume level by 1 step,Press and hold“VOL +” increase the volume level continuously；
– Volume range is from 0 to 31, OLED displays the corresponding volume icon and level .
Remark: Long press Power key for 10s to restore to factory default volume 31.
GAIN Adjustment
– In “Smartphone Mode”and “PC Mode”.
– Single press key“GAIN”（same as key“MFB”）to adjust the earphone Gain to HIGHT or LOW，OLED display ”GAIN H”和 ”GAIN L”accordingly to fit different impedance of earphones。
Remark: Long press Power key for 10s to restore to factory default Gain high.
Battery function
Battery Charge
– Connect the charging cable (5V 2A) via the charging port，
– In Woring mode，OLED display the charing status 
。
– In Off mode，Connect the charing cable will wake up the unit and display the charging stauts。
Battery level indicator
– In working mode，OLED display the corresponding volume level .
Remark：
-When battery is low, OLED will display Low battery and indicate the user to charge.
Power On and Power Off
– Press and Hold Key “POWER”for 2s，M18i will power on，OLED display start logo “Questyle” and enter the selected Audio Source input mode(Bluetooth/PC/Smartphone modes).
– After power on，OLED will display Audio source, audio format, audio sample rate accordingly.
– Press and Hold Key “POWER”for 2s again to power off the unit ，OLED display turns off.
Remark:
– When no key pressed for 1 minute. the unit will enter DIM mode, at this time the OLED dim off
to 20% brightness. in DIM mode, operate key press will enter DIM mode and OLED returns to 100% brightness.
– When no key pressed and no USB audio input and no Bluetooth device connected for about 4 minutes, the M18i then will auto enter power off mode to save battery。
Packing and Accessories
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.
Any changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.
NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation.
If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
— Reorient or relocate the receiving antenna.
— Increase the separation between the equipment and receiver.
— Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
— Consult the dealer or an experienced radio/TV technician for help.
The device has been evaluated to meet general RF exposure requirement. The device can be used in portable exposure condition without restriction.
Documents / Resources
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