S.M.S.L M300SE HiFi Headphone Amplifier & DAC User Manual

1. Product Overview

The S.M.S.L M300SE is an advanced HiFi Headphone Amplifier and Digital-to-Analog Converter (DAC) designed to deliver high-fidelity audio. It incorporates two CS43131 MQA Audio DAC chips, an XMOS XU-316 processor, and supports various input options including USB, Optical, Coaxial, and Bluetooth. The device features both single-ended and balanced headphone outputs, as well as balanced XLR and single-ended RCA line outputs.

Front view of the S.M.S.L M300SE, showcasing its compact design and clear display.

Key Features:

• High-Resolution Audio Support: Capable of directly sampling PCM digital audio up to 32-bit/768kHz and Native DSD playback up to DSD256. Optical/Coaxial input supports DoP64.
• Integrated Headphone Amplifier: Features 6.35mm single-ended and 4.4mm balanced headphone jacks with substantial driving power and automatic impedance detection.
• Full MQA Decoding: Provides complete MQA decoding to fully expand MQA music files for high-quality sound reproduction.
• Pure DAC Mode: Allows disabling volume control in preamp mode, providing fixed output levels (4.0Vrms XLR balanced, 2.0Vrms RCA single) for use as a pure DAC.
• Ultra-Low Distortion: Achieves a THD+N as low as 0.00013%.

2. Setup Guide

This section details the steps to set up your S.M.S.L M300SE for optimal performance.

2.1 Unpacking and Components

Carefully remove all items from the packaging. The box should contain the following:

• S.M.S.L M300SE Unit
• USB Type-C Cable
• Bluetooth Antenna
• Infrared Remote Control (RC-8C)
• User Manual (this document)

Package contents of the S.M.S.L M300SE.

2.2 Connecting Power

The M300SE is powered via its USB-C input. Connect the provided USB Type-C cable to the 'USB' port on the rear of the unit and to a compatible USB power source (e.g., a computer USB port or a 5V USB charger). If using a phone as a source or if the primary USB source does not provide sufficient power, connect an additional 5V DC power supply to the 'AUX POWER' USB-C port to prevent overcurrent issues. Do not use Quick-Charge power supplies over 5V with this unit.

2.3 Input Connections

The M300SE supports multiple digital audio inputs:

• USB Input: Connect your computer or digital audio player to the 'USB' port using the provided USB Type-C cable.
• Optical Input: Connect an optical audio cable from your source device to the 'OPTICAL' port.
• Coaxial Input: Connect a coaxial audio cable from your source device to the 'COAXIAL' port.
• Bluetooth Input: Screw the provided Bluetooth antenna onto the 'Y' connector on the rear panel. Enable Bluetooth on your source device and pair with 'S.M.S.L M300SE'.

2.4 Output Connections

The M300SE offers various audio outputs:

• Headphone Outputs: Connect your headphones to either the 6.35mm single-ended or 4.4mm balanced headphone jack on the front panel.
• Balanced XLR Output: For connecting to balanced amplifiers or active speakers, use XLR cables with the 'BAL-R' and 'BAL-L' ports.
• Single-Ended RCA Output: For connecting to single-ended amplifiers or active speakers, use a 3.5mm to RCA cable with the 'SE' port.

Detailed view of the S.M.S.L M300SE's front and rear connections.

3. Operating Instructions

Learn how to operate your S.M.S.L M300SE and utilize its various functions.

3.1 Power On/Off

Press the top power button on the front panel or the power button on the remote control to turn the unit on or off.

3.2 Volume Control

Rotate the knob on the front panel clockwise to increase volume and counter-clockwise to decrease volume. Volume can also be adjusted using the '+' and '-' buttons on the remote control.

3.3 Input Selection

Press the bottom button on the front panel or the 'Switch input' button on the remote control to cycle through available inputs (USB, Optical, Coaxial, Bluetooth).

3.4 Remote Control Functions

The included RC-8C infrared remote control provides convenient access to various settings:

• ON/OFF: Power on/off the unit.
• Menu: Access system settings (no function on this model).
• Next/Previous: (No function on this model).
• Switch Input: Cycle through input sources.
• Mute: Mute/unmute audio output.
• Switch to Bluetooth Input: Directly select Bluetooth input.
• Volume Up/Down: Adjust volume level.

Functions of the S.M.S.L RC-8C infrared remote control.

3.5 MQA Playback

When playing MQA audio files, the M300SE will automatically detect and fully decode the MQA stream, indicated on the display. This ensures you experience the full quality of the original master recording.

Explanation of MQA full decoding support.

3.6 Preamp Mode / Pure DAC Mode

The M300SE can operate in a preamp mode with volume control or as a pure DAC with fixed output. To use it as a pure DAC, you can turn off the volume control function in the menu settings. In this mode, the output level will be fixed at 4.0Vrms for XLR balanced output and 2.0Vrms for RCA single-ended output.

4. Maintenance

To ensure the longevity and optimal performance of your S.M.S.L M300SE, follow these maintenance guidelines:

• Cleaning: Use a soft, dry cloth to wipe the exterior of the unit. Avoid using abrasive cleaners, solvents, or chemical sprays, as these can damage the finish.
• Placement: Place the unit on a stable, flat surface away from direct sunlight, heat sources, and excessive moisture. Ensure adequate ventilation around the unit to prevent overheating.
• Connections: Periodically check all cable connections to ensure they are secure and free from dust or corrosion.
• Storage: If storing the unit for an extended period, disconnect it from power and store it in a cool, dry place.

5. Troubleshooting

If you encounter issues with your S.M.S.L M300SE, refer to the following common problems and solutions:

If the problem persists after trying these solutions, please contact S.M.S.L customer support or your retailer for further assistance.

6. Specifications

Detailed technical specifications for the S.M.S.L M300SE.

The S.M.S.L M300SE utilizes dual CS43131 DAC chips for high-quality audio.

The third-generation XMOS XU-316 high-end independent main control chip.

7. Warranty and Support

The S.M.S.L M300SE comes with a 12-month warranty from the date of purchase. This warranty covers manufacturing defects and malfunctions under normal use. If you experience any issues with your product within the warranty period, you may be eligible for a return or replacement.

For technical support, warranty claims, or service inquiries, please contact your original retailer or visit the official S.M.S.L website for contact information. Please retain your proof of purchase for warranty validation.