Questyle M18i Review – Dongle DAC-AMP With Bluetooth
The Questyle M18i combines the best of both worlds with Bluetooth and wired mobile lossless decoding. Featuring dual ES9219Q DAC chips and an advanced “current mode” amplifier, it delivers stunning audio performance whether you’re using wired or wireless headphones.
Questyle’s M18i features the brand’s signature current mode amplification technology. This innovative approach, developed by the brand’s founder Wang Fengshuo, sets itself apart by processing the signal as a current rather than a voltage and uses transistors within a fully discrete architecture operating in pure Class A to deliver the best possible output. This approach has many advantages, including a significant reduction in transient intermodulation distortion (TIMD), much higher bandwidth, and extremely low harmonic distortion.
The M18i contains four sets of SiP modules providing both powerful drive and delicate timbre. The M18i also features ESS’s flagship ES9219Q Combo DAC, a dual-DAC mono design, and a TTA (Three-Tier Architecture) DAC framework. Together, these provide performance equivalent to large desktop devices, while raising the bar for portable sound quality.
The Questyle M18i features wired USB and dual-mode lossless Bluetooth connectivity, powered by a 16-core XMOS316 USB platform for seamless compatibility with smartphones, PCs, and gaming consoles.
As the first M-series product with Qualcomm Snapdragon Sound, the M18i also introduces intelligent battery management, a high-definition OLED screen, and a microphone for clear voice calls. Offering exceptional Hi-Fi audio via Bluetooth or USB, the M18i delivers a premium listening experience.
The “i” in M15i indicates that it has been certified by Apple’s MFi. MFi certification ensures perfect support for iPhone/iPad and seamless integration into the Apple ecosystem. It complies with Apple’s stringent requirements for external devices regarding power consumption and compatibility, avoiding the risk of damage to phones and systems from arbitrary device pairings.
The Questyle M18i prioritizes resolving trade-offs between size, power efficiency, and audio performance in portable, battery-powered devices. It features two patented quad-core Current Mode Amplifier (CMA) SiP modules, delivering powerful drive with delicate timbre and achieving ultra-low distortion of 0.0002%.
Combining CMA technology with TOREX’s high-efficiency power management, the M18i ensures low power consumption without compromising performance, setting a new benchmark for the Questyle M series.
The M18i supports lossless Bluetooth and USB DAC dual-mode switching, making it convenient for users to choose freely. It is equipped with the latest generation of Qualcomm Snapdragon Sound technology and Bluetooth 5.4.
The M18i, equipped with (x4) current mode engines, supports 3.5mm single-ended and 4.4mm fully balanced output modes. It also features manual gain adjustment, allowing users to choose the gain mode according to personal preferences, headphone characteristics, or the audio system.
Management System
Mobile Mode
In Mobile Mode, the USB audio port is used exclusively for data transmission and does not draw power from the connected mobile device. The M18i operates entirely on its internal battery. Similarly, in Bluetooth Mode, the device relies solely on its battery for power, ensuring no external power source is required.
M18i supports lossless Bluetooth & USB DAC dual-mode switching, which is convenient for users to choose freely. Has a unique advantage in Bluetooth performance, it is equipped with the latest generation of Qualcomm Qualcomm (SnapdragonSoundTM) technology products, up to 5.4 Bluetooth Version, which not only supports mainstream AAC and SBC encodings, but also supports more lossless aptX-HD, aptX Adaptive, and the latest LE Audio Coding. The M18i also supports 24bit/96kHz LDAC encoding. This means that as long as the front-end equipment also supports these Bluetooth encoding formats.
PC Mode
In PC Mode, the USB audio port serves a dual purpose: transmitting data and supplying power. It charges the M18i’s battery while simultaneously powering the system.
When connected to a USB host device with a current limit, the M18i intelligently manages power distribution. It prioritizes the system’s operation by ensuring stable performance, then dynamically adjusts the battery charging current based on the system’s workload and power availability. This ensures optimal performance without overloading the USB host.
Features
- Dual flagship ES9219Q DACs
- Equipped with Bluetooth 5.4
- 3.5mm and 4.4mm outputs for versatile headphone compatibility
- The ultra-low noise floor of -130dB for a pure background and real sound
- Supports up to 384kHz (16/24/32-bit) PCM, delivering rich, high-fidelity audio
- Fully compatible with iOS, HarmonyOS, and Android.
- Fully laminated OLED Screen
- Charge while using in USB-C Mode
- Support HD Calls with Advanced Noise Reduction Technology
- Supports Windows 10/11 and macOS, as well as PSP gaming consoles.
Specs
- Material: CNC Anodized Aluminum Alloy
- Color: Black
- Size: 75mm x 35mm x 14.5mm
- Bluetooth Version 5.4
- Supports: AAC, SBC, aptX, aptXHD, aptX adaptive, LDAC, LE Audio
- PCM: PCM: 44.1kHz-384kHz (16/24/32bit)
- DSD: DSD64, DSD128, DSD256
- Output Power 4.4mm: 28mW @ 300 ohms
- Frequency Response: ±0.1dB (20Hz-20kHz); ±2dB (20Hz-80kHz)
- THD+N: 0.0002%
- DAC: (2x) ESS ES9219Q
Compatible Operating Systems
- Android phones and tablets: Android 5.0 and above
- PC: Win10 1803 and above
- Apple cellphone: iOS (You need to buy an OTG cable for Lightning to USB-C)
- Apple computer: Mac OS
Price: $349
I want to thank Questyle for sending me the review sample of the M18i.
In the Box
- M18i Dongle DAC
- USB Type-C to Type-C cable
- USB Type-C to Type-A adapter
- Warranty Card
- User Manual
Sound
A low-noise floor is essential for capturing the intricate details of an audio track, allowing you to experience true high fidelity. As verified in a controlled laboratory testing environment, the M18i excels, delivering exceptional accuracy with an ultra-low noise floor of -130dB.
The Questyle M18i delivers a seamless and harmonious sound throughout the entire range, showcasing an abundance of intricacies. Its tonal balance remains neutral, preserving the authentic sound without any alterations. The sound quality is pristine and articulate, featuring rapid and precisely managed transients.
It presents itself as a versatile performer, offering a satisfying listening journey, irrespective of the chosen IEM. The majority of combinations produce a clear and consistent sound, characterized by excellent dynamics. The Questyle M18i provides a completely silent background on 3.5mm and 4.4mm ports, with no hissing or humming.
Lows
The bass response on the Questyle M18i is neutral with great punch. I never missed a kick drum beat and the separation between low-end instruments was phenomenal. Especially on the Focal’s, which are known for their dynamics, I got a great sense of slam without it ever becoming too much. The sub-bass rumble is present without causing any bias towards the low end and the transitional space between mid-bass and lower-mids is smooth and transparent.
The Questyle M18i’s low range delivers a tight, quick, and well-rounded sound. The bass level is just right and precise, without overshadowing the midrange or blending with other frequencies. It is well-managed and rich in texture.
Mids
I found the midrange to be neutral-warm. Vocals are clear and natural without feeling too forward. What stood out to me was the sense of micro dynamics of which the Questyle M18i is. Sounds like violin pans had a great attack while moving within the stereo range. Meanwhile, I could hear the decay of reverb-laden vocals with crystal clarity.
The vocals are positioned accurately, and the midrange as a whole feels musical and dynamic due to its warm tonality. The Questyle M18i effectively combines accuracy with a natural timbre, resulting in a precise tone
Midrange detail is also fantastic. I could hear the sounds of the guitarist’s fingers moving up and down the fretboard. Instrument notes are all handled with care. You can feel the impact of snare drum hits and guitar strums. All in all, the midrange of the Questyle M18i is nuanced, detailed, and natural.
Highs
The Questyle M18i delivers a crisp and precise treble reproduction, showcasing an abundance of details. The extensions are well-maintained and controlled, ensuring a pleasant listening experience without any sense of deficiency.
I’ll use the word decay again to describe how the high-end resolves. Sounds don’t just end, they shimmer and fade like sound naturally does. There’s no distortion that I can hear, just high-resolution sound.
Soundstage
Off the bat, the soundstage on this device was impressive to me. It has a great sense of space and sound placement. What I enjoyed the most, though, was the imaging and separation of the DAC/amp. I could hear every sound and where it was coming from. But even more impressive is I could hear the open space on the track and locate where it was.
Not only could I hear the detailed imaging of the different cymbals as they crashed, but I could also get a sense of the space they recorded as the musicians built from quiet to loud. Overall, this is an impressive amp for imaging and processing details to the point that it feels like you’re in the room with the musicians.
Sum-Up
The Questyle M18i is a remarkable upgrade in Bluetooth audio amplifiers. It blends style with strong performance, making it suitable for casual listeners and dedicated audiophiles. It’s easily the best portable Bluetooth DAC-AMP of 2024-2025 in any price range.
If you want to improve your current audio setup or explore high-quality sound, the Questyle M18i is a top option that offers both style and quality. For those wishing to enhance their listening experience, the Questyle M18i might be just what you need.