Fosi Audio MD3 Portable DAC/Headphone Amplifier

Description

About the Fosi Audio MD3 Portable DAC/Headphone Amplifier

The Fosi Audio MD3 Portable DAC/Headphone Amplifier has a magnetic rear panel that attaches to MagSafe-compatible phones and cases. Therefore, the MD3 sits neatly behind your device instead of hanging from a conventional dongle cable.

Inside, an ESS Sabre ES9039Q2M DAC supports PCM audio up to 32-bit/384kHz and native DSD256. Four ESS ES9603Q amplifier chips then drive either conventional 3.5mm headphones or a balanced 4.4mm connection.

The MD3 also includes dual USB-C ports, pass-through phone charging, physical volume controls, and a customisable 1.28-inch circular display.

What We Think

The MD3 brings some welcome personality to the portable DAC market.

Most dongle DACs are small metal boxes that hang beneath your phone. In comparison, the MD3 uses a magnetic mounting system to create a tidier and more integrated setup. Its circular screen, orange controls, and custom graphics also make it feel more considered than a basic audio adaptor.

More importantly, its audio hardware is credible. The ES9039Q2M DAC and four-chip balanced amplifier deliver a clean signal with useful power for IEMs, portable headphones, and many efficient over-ear models.

The 4.4mm output is the connection to choose when compatible headphones are available. It offers up to 180mW per channel into 32 ohms, compared with at least 80mW through the 3.5mm output.

However, the Fosi Audio MD3 Portable DAC/Headphone Amplifier is not intended to replace a powerful desktop headphone amplifier. Demanding planar-magnetic headphones and inefficient full-size designs may need more output headroom. It also has no Bluetooth, so a wired USB connection is always required.

For everyday wired listening from a modern smartphone, the MD3 offers an attractive balance of sound quality, convenience, construction, and visual character.

 

 

View Product Manual & Support >> View Fosi Audio Products >>

 

The Fosi Audio MD3 Portable DAC/Headphone Amplifier Is Ideal For

• Smartphone owners wanting better wired headphone sound
• MagSafe-compatible iPhone and phone-case users
• Listeners who prefer wired IEMs over wireless earbuds
• Buyers wanting both 3.5mm and 4.4mm outputs
• Lossless and high-resolution music playback
• Portable headphones that benefit from more power
• Laptop and desktop headphone listening
• Buyers wanting pass-through phone charging
• Users who prefer physical volume controls
• Listeners who enjoy a customisable display
• Travel, commuting, office, and bedside listening
• Anyone who finds a conventional dangling dongle inconvenient

 

Reviews & Comments

• Headfonics awarded the MD3 7.9 overall. The reviewer praised its neutral and transparent presentation, micro-detail retrieval, spacious soundstage, compact construction, and playful display. However, he felt that output power could be higher.
• Headfonia praised the MD3’s aluminium construction, precise finish, quiet background, and clean presentation. The reviewer found it powerful enough for most portable headphones but noted that demanding full-size planar headphones could exceed its comfortable limits.
• Pragmatic Audio described the MD3 as clean, neutral, and transparent. The reviewer found its balanced output suitable for most portable headphones and IEMs, while power-hungry over-ear models such as the Sennheiser HD600 benefited from additional amplification.

 

Frequently Asked Questions

1. What does the Fosi Audio MD3 do?
   The MD3 converts digital audio from a compatible phone, tablet, computer, or gaming device into an analogue signal for wired headphones. Its integrated headphone amplifier provides more drive than a basic passive USB headphone adaptor.
2. Does the MD3 connect wirelessly to a phone?
   The magnetic system holds the MD3 against the phone, but it does not transmit audio. Music travels through a wired USB-C connection. The MD3 does not include Bluetooth or Wi-Fi.
3. Will the MD3 work with an iPhone?
   It is best suited to USB-C iPhones with MagSafe support or a compatible magnetic case. Older Lightning-equipped iPhones may require an appropriate digital adaptor and cable. Compatibility should be confirmed before purchase.
4. Will the Fosi Audio MD3 work with Android phones?
   Yes, provided the phone supports USB Audio output and can supply the required power. A magnetic case or adaptor ring may be needed if the phone does not include a MagSafe-compatible mounting system.
5. What is the difference between the 3.5mm and 4.4mm outputs?
   The 3.5mm output is compatible with most conventional wired headphones and provides at least 80mW per channel into 32 ohms. The balanced 4.4mm output delivers at least 180mW per channel into 32 ohms and requires a correctly wired balanced headphone cable.
6. Can I use a 3.5mm headphone with the 4.4mm output through an adaptor?
   Only use an adaptor specifically designed for the required connection. A basic single-ended-to-balanced adaptor can short parts of the balanced amplifier circuit and may damage the MD3. If unsure, use the native 3.5mm socket.
7. Will the MD3 drive full-size headphones
   It can drive many efficient full-size headphones, particularly through the 4.4mm output. However, demanding planar-magnetic headphones and inefficient high-impedance models may require a more powerful desktop amplifier. Impedance alone does not determine how difficult a headphone is to drive.
8. Is the MD3 suitable for sensitive IEMs?
   Its low published noise floor and 100-step volume adjustment make it a promising match for sensitive IEMs. Start with low gain and a low volume setting before inserting the earphones.
9. Does the Fosi Audio MD3 have an internal battery?
   Fosi Audio does not publish a battery capacity or independent operating time. The MD3 operates from USB power and supports a dual-port arrangement that allows the connected phone to charge while audio is playing.
10. Can I charge my phone while using the MD3?
    Pass-through charging is one of the MD3’s main features. Connect the source and external power according to Fosi Audio’s instructions. Charging speed will depend on the phone, charger, cable, and power-delivery compatibility.
11. Does the MD3 support high-resolution audio?
    In UAC 2.0 mode, it supports PCM audio up to 32-bit/384kHz and native DSD256. UAC 1.0 mode is limited to PCM at up to 16-bit/48kHz but may offer wider device compatibility.
12. What information does the screen display?
    The 1.28-inch circular screen can show volume, gain, sample rate, filter information, operating status, animations, and compatible custom images. It can rotate for different orientations but is not a touchscreen.
13. Can the MD3 attach to a phone through a case?
    Yes, if the case is MagSafe compatible or contains a suitably positioned magnetic ring. Thick or non-magnetic cases may weaken or prevent the attachment. Cable weight and headphone-plug shape can also affect how securely the unit stays in position.
14. Can I use the MD3 as a desktop DAC?
    Yes, it can connect to a compatible Windows or macOS computer for headphone listening. However, it does not have a dedicated fixed line output, RCA sockets, or powerful desktop amplification. A full-size DAC and headphone amplifier may be more suitable for a permanent system.

 

Key Features

Magnetic Phone Attachment

The MD3 contains a magnetic rear mounting system designed for MagSafe-compatible phones and cases.

This keeps the DAC close to your device and reduces the movement associated with a hanging dongle. A compatible magnetic case or adhesive ring may be required for phones without an integrated magnetic mounting system.

ESS Sabre ES9039Q2M DAC

An ESS Sabre ES9039Q2M handles digital-to-analogue conversion.

It supports PCM audio up to 32-bit/384kHz and native DSD256 through UAC 2.0. As a result, the MD3 can reproduce standard streaming audio, lossless music, and compatible high-resolution files.

Four ESS ES9603Q Amplifier Chips

Fosi Audio uses four ES9603Q amplifier chips to support the MD3’s headphone outputs.

The balanced 4.4mm connection delivers at least 180mW per channel into 32 ohms. Meanwhile, the single-ended 3.5mm output provides at least 80mW per channel into the same load.

3.5mm and 4.4mm Headphone Outputs

A standard 3.5mm socket supports conventional wired headphones and earphones.

The 4.4mm Pentaconn output suits headphones fitted with a compatible balanced cable. It also provides the MD3’s highest published output power.

Dual USB-C Connections

Two USB-C ports provide flexible connection and charging arrangements.

The top port supports audio decoding, image transfer, and external power. The lower port supports audio decoding, image transfer, and firmware upgrades. The dual-port design also enables pass-through phone charging in a compatible setup.

Listen While Charging

The MD3 allows your connected phone to receive power while music continues playing.

This is especially useful during travel, long listening sessions, gaming, or desk use. However, the DAC still needs a wired connection to the source.

UAC 1.0 and UAC 2.0 Support

UAC 2.0 provides access to PCM playback up to 32-bit/384kHz and native DSD256.

UAC 1.0 supports PCM up to 16-bit/48kHz. It can improve compatibility with older computers and certain gaming devices that do not support UAC 2.0.

1.28-Inch Circular Display

The rotatable circular LCD shows volume, operating information, playback format, and visual themes.

It can display supplied graphics, animations, or compatible custom images. The screen is not touch-sensitive, so operation remains button-based.

Physical Volume and Menu Controls

Dedicated side buttons provide direct volume adjustment and menu navigation.

A 100-step volume system allows relatively fine adjustment. This is especially useful with sensitive IEMs, where large volume jumps can be uncomfortable.

Vista Button and Custom Graphics

The orange Vista button provides quick access to visual content.

You can browse uploaded pictures, supplied animations, and novelty features. Built-in mini-games include dice, spin the bottle, and rock paper scissors.

Low Published Noise

Fosi Audio publishes a noise floor below 1.7μV through the 3.5mm output and below 2.7μV through the 4.4mm output.

This makes the MD3 particularly relevant for sensitive IEMs. However, perceived hiss will still depend on the earphones, gain setting, source, and listening environment.

Compact Aluminium Construction

The MD3 measures only 70 × 45 × 12mm and weighs approximately 50g without its cable.

Its aluminium-alloy enclosure provides a more substantial feel than a typical plastic phone adaptor while remaining pocket-friendly.

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System Match Ideas

The Fosi Audio MD3 Portable DAC/Headphone Amplifier is best matched with a USB-C smartphone, a MagSafe-compatible case, and a quality pair of wired IEMs.

Attach the MD3 to the rear of the phone, then connect it with the supplied short USB-C cable. The magnetic arrangement keeps both devices together while the short cable carries digital audio.

Standard earphones can use the 3.5mm output. However, headphones with a compatible 4.4mm balanced cable can access the higher 180mW-per-channel output.

Start at a low volume, especially with sensitive IEMs. Then increase the level gradually. If the headphones sound compressed or lack dynamic impact at higher volumes, they may require a more powerful desktop or transportable amplifier.

For longer sessions, connect power through the appropriate USB-C port to charge the phone while listening

 

Specifications

Brand: Fosi Audio
Model: MD3
Product Name: MD3 MagDac
Product Type: Portable USB DAC and headphone amplifier
DAC Chip: ESS Sabre ES9039Q2M
Headphone Amplifier Chips: Four ESS ES9603Q chips
Digital Inputs: Two USB-C ports
Top USB-C Functions: Audio decoding, image transfer, and power input
Bottom USB-C Functions: Audio decoding, image transfer, and firmware upgrade
Pass-Through Phone Charging: Yes, with a compatible connection arrangement
USB Audio Classes: UAC 1.0 and UAC 2.0
Maximum UAC 2.0 PCM Resolution: 32-bit/384kHz
Maximum UAC 2.0 DSD Resolution: Native DSD256
Maximum UAC 1.0 Resolution: PCM 16-bit/48kHz
Single-Ended Headphone Output: 3.5mm
Balanced Headphone Output: 4.4mm Pentaconn
3.5mm Output Power: At least 80mW × 2 into 32 ohms
4.4mm Output Power: At least 180mW × 2 into 32 ohms
Published Headphone Impedance Range: 16 to 300 ohms
Frequency Response: 20Hz to 48kHz, ±0.2dB
3.5mm Signal-to-Noise Ratio: At least 115dB
4.4mm Signal-to-Noise Ratio: At least 116dB
3.5mm Dynamic Range: At least 115dB
4.4mm Dynamic Range: At least 116dB
3.5mm THD+N: No more than 0.00075%
4.4mm THD+N: No more than 0.00084%
3.5mm Noise Floor: Below 1.7μV
4.4mm Noise Floor: Below 2.7μV
Volume Adjustment: 100 steps
Gain Adjustment: Yes
Display: 1.28-inch circular LCD
Display Rotation: Yes
Touchscreen: No
Custom Images: Yes
Built-In Animations: Yes
Built-In Mini-Games: Yes
Magnetic Mounting: Yes
Magnet Type: N52 neodymium
Published Magnet Quantity: 16
Bluetooth: No
Wi-Fi: No
Analogue Audio Input: No
Line Output: No dedicated fixed line output published
Integrated Battery: No battery capacity or independent runtime is published
Power Arrangement: USB-powered with pass-through phone charging support
Chassis Material: Aluminium alloy
Rear Surface: Orange leather-style protective panel
Dimensions: 70 × 45 × 12mm
Weight: 50g, ±2g, without cable
Colours: Galaxy and Obsidian
Firmware Updates: Supported through USB-C

Standard Published Package Contents:

• Fosi Audio MD3
• USB-C connection accessory
• User manual
• Quick guide

Rapallo Product Data

EAN: Not publicly published
UPC: Not publicly published
GTIN: Not publicly published
Manufacturer Part Number: MD3

 

Why Buy From Rapallo

✔ Practical advice from experienced New Zealand audio specialists
✔ Help matching the MD3 with suitable headphones and IEMs
✔ Guidance on 3.5mm and 4.4mm connections
✔ Advice on USB-C, phone, tablet, and computer compatibility
✔ Assistance choosing balanced headphone cables
✔ Help understanding PCM, DSD, UAC 1.0, and UAC 2.0
✔ Carefully selected portable audio accessories
✔ New Zealand-based service and after-sales support
✔ Secure nationwide delivery
✔ Support before and after your purchase