1. Introduction and Overview
The Questyle M18i is a high-resolution portable USB DAC and headphone amplifier designed to enhance your audio experience across various devices. Featuring Bluetooth 5.4 connectivity, dual 4.4mm balanced and 3.5mm unbalanced outputs, and support for advanced codecs like LDAC, it delivers lossless audio quality for smartphones, PCs, and laptops. Its compact design integrates cutting-edge technology, including the ESS ES9219Q DAC chip and Questyle's patented Current Mode Amplifier SiP modules, ensuring exceptional sound performance with ultra-low distortion.
Figure 1.1: Questyle M18i Headphone Amplifier
2. Key Features
- Advanced DAC Performance: Equipped with the latest ESS flagship ES9219Q DAC chip, utilizing Questyle and ESS's collaborative TTA DAC framework for optimal performance.
- Current Mode Amplification: Features two patented quad-core Current Mode Amplifier SiP modules, providing powerful drive, delicate timbre, and an ultra-low distortion record of 0.0002%.
- Versatile Outputs and Controls: Offers both 3.5mm unbalanced and 4.4mm balanced outputs. Includes manual gain control for various headphones and an MFB button for Bluetooth functions. Volume buttons provide 60 levels of loudness.
- Seamless Bluetooth and USB DAC Modes: Supports seamless switching between lossless Bluetooth and USB DAC modes.
- Qualcomm Snapdragon Sound Technology: Integrates Qualcomm's latest Snapdragon Sound technology with Bluetooth 5.4, supporting AAC, SBC, aptX, aptX HD, aptX Adaptive, LE AUDIO, and 24bit/96kHz LDAC for wireless lossless audio.
- Enhanced Call Quality: Incorporates Qualcomm's cVc Generation 8.0 call solution with ClearVoice Capture technology and an Infineon flagship microphone for crystal-clear voice calls with noise suppression.
3. Package Contents
Please ensure all items are present in the package:
- Questyle M18i Headphone Amplifier
- USB-C to USB-C Cable
4. Product Diagram and Components
Familiarize yourself with the various parts and connections of your M18i device.
Figure 4.1: M18i Internal Components and PCB Layout
Key components include:
- 1. Patented SP Current Mode Amplifier module: US 9,614,483 B2
- 2. ESS Flagship USB DAC: ES9219Q x 2
- 3. 4.4mm balanced headphone jack
- 4. Torex power management system
- 5. Asynchronous Clock Patented Architecture
- 6. USB Type-C Charging Port
- 7. Infineon's flagship microphone
- 8. USB Type-C Data Port
- 9. 3.5mm headphone jack
- 10. Gain/MFB button: (Multi-function button only for BT Mode)
- 11. Bluetooth & PC/Phone Mode Switch
- 12. XMOS USB DAC
- MCU Controller
- Qualcomm Bluetooth Module
- OLED Display
Figure 4.2: 4.4mm and 3.5mm Dual Outputs
5. Setup
5.1 Initial Charging
Before first use, fully charge your M18i. Connect the provided USB-C cable to the M18i's USB Type-C Charging Port and the other end to a compatible USB power source (e.g., computer USB port, wall adapter). The charging time is approximately 2 hours.
5.2 Connecting Headphones
The M18i features both 3.5mm unbalanced and 4.4mm balanced headphone jacks. Insert your headphone cable into the appropriate jack. Ensure the connection is secure.
5.3 Device Connection
The M18i supports connection to various systems including Android, iOS, Windows, and Mac devices. Use the appropriate USB-C cable to connect the M18i to your smartphone, PC, tablet, or laptop.
Figure 5.1: M18i Compatibility with Various Platforms
6. Operating Instructions
6.1 Mode Selection (Bluetooth / PC / Phone)
Use the dedicated switch on the M18i to select between Bluetooth, PC, or Phone mode.
6.1.1 Phone Mode
In Phone Mode, the M18i operates using its internal battery for power. The USB audio port is solely for data transfer and does not draw or supply power to the connected phone.
Figure 6.1: M18i in Phone Mode
6.1.2 Bluetooth Mode
In Bluetooth Mode, the M18i also relies exclusively on its battery for power supply. To pair, switch to Bluetooth mode, then search for 'Questyle M18i' on your device's Bluetooth settings and connect.
Figure 6.2: M18i in Bluetooth Mode
6.1.3 PC Mode
In PC Mode, the M18i's USB audio port can transfer data and supply power to charge the battery or provide power to the system. When connected to a phone in PC mode, the M18i will consume the phone's battery power.
Figure 6.3: M18i in PC Mode
6.2 Gain Switch
In Phone or PC mode, press the "GAIN/MFB" button to switch between HIGH/LOW gain settings. This allows you to match the impedance of different headphones for optimal audio output.
Figure 6.4: Gain Switch Location
6.3 MFB Button (Multi-Function Button)
The MFB multi-function button is only operable in Bluetooth mode.
- Music Playback: During playback in Bluetooth connected state, click the "MFB" button once to toggle between Pause and Play. Click it twice to skip to the next track.
- Call Management: When a call comes in while playing in Bluetooth connected state, click the "MFB" button once to answer the call. Click it twice to reject the call. During an active call, click it once to end the call.
Figure 6.5: MFB Button Location
6.4 Volume Control
Use the dedicated volume buttons (+ and -) on the M18i to adjust the loudness. The device provides 60 levels of volume control.
7. Maintenance
To ensure the longevity and optimal performance of your Questyle M18i, follow these maintenance guidelines:
- Cleaning: Use a soft, dry, lint-free cloth to clean the exterior of the device. Avoid using harsh chemicals, cleaning solvents, or strong detergents, as they may damage the finish or internal components.
- Storage: When not in use, store the M18i in a cool, dry place, away from direct sunlight, extreme temperatures, and high humidity.
- Handling: Handle the device with care. Avoid dropping it or subjecting it to strong impacts, which can damage internal circuitry.
- Connectivity Ports: Keep the headphone jacks and USB-C ports free from dust and debris. You may use a can of compressed air to gently clear any obstructions.
- Charging: Always use the provided cable or a high-quality, compatible USB-C cable for charging to prevent potential damage to the battery or charging port.
8. Troubleshooting
If you encounter issues with your M18i, please refer to the following common problems and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| No sound output | Incorrect mode selected; Loose headphone connection; Low device volume; Device not powered on. | Ensure correct mode (Phone/PC/Bluetooth) is selected. Check headphone connection. Increase volume on M18i and source device. Power on the M18i. |
| Bluetooth connection issues | M18i not in pairing mode; Interference; Previously paired device interfering. | Ensure M18i is in Bluetooth mode and discoverable. Move closer to the source device. Turn off Bluetooth on other nearby devices. Try forgetting and re-pairing the M18i on your source device. |
| Poor sound quality (distortion, low volume) | Incorrect gain setting; Low quality audio source; Damaged cable/headphones. | Adjust the gain setting (HIGH/LOW) to match your headphones. Ensure you are playing high-quality audio files. Test with different headphones or cables. |
| Short battery life | High volume usage; Bluetooth mode (higher power consumption); Old battery. | Reduce volume. Consider using PC mode for extended listening as it can draw power from the host. Ensure the device is fully charged before use. |
| Device not charging | Faulty cable/charger; Dirty charging port. | Try a different USB-C cable and power adapter. Clean the USB-C charging port gently. |
If the problem persists after trying these solutions, please contact Questyle customer support for further assistance.
9. Specifications
| Specification | Value |
|---|---|
| Model Name | M18i |
| Brand | Questyle |
| Connectivity Technology | Bluetooth, USB |
| Wireless Communication Technology | Bluetooth 5.4 |
| Headphones Jack | 3.5 mm Jack, 4.4 mm Balanced |
| Compatible Devices | Cellphones, Smartphone, Various systems including Android, iOS, Windows, Mac, and devices like phones, computers, tablets, laptops, audio players, and car audio systems. |
| Material | Aluminum |
| Item Weight | 0.14 Kilograms (approx. 5 ounces) |
| Control Method | Push Button |
| Charging Time | 2 Hours |
| Impedance | 300 Ohm |
| DAC Chip | ESS ES9219Q x 2 |
| Supported Audio Codecs | AAC, SBC, aptX, aptX HD, aptX Adaptive, LE AUDIO, LDAC |
| Max Resolution (USB DAC) | PCM 384kHz/DSD256 |
| Microphone | Infineon flagship microphone with cVc Generation 8.0 |
10. Warranty and Support
The Questyle M18i is sold by Questyle, ensuring direct support from the manufacturer. For specific warranty details, please refer to the warranty card included with your product or visit the official Questyle website. For technical support, troubleshooting assistance beyond this manual, or service inquiries, please contact Questyle customer support through their official channels.
Questyle Official Website: www.questyle.com
Please retain your proof of purchase for warranty claims.
