Questyle M18i Review

Today, we review the $349 USD Questyle M18i USB DAC/AMP dongle with Bluetooth.

Disclaimer: Questyle sent us the M18i for this review. As always, I’m here to share my honest opinion about the product.

Questyle

With over 10 years of experience in the audio field, Questyle has been focused on the research, design, and development of high-performance audio equipment. They’ve built a solid reputation through both desktop and mobile products and have released several award-winning devices over the years.

My experience with Questyle dates back to 2015. They had just released a portable player called the QP1, and I was genuinely impressed with its performance at the time. More recently, their portable DAC/AMPs have started gaining more recognition globally, and I’ve noticed a rise in popularity within the audiophile community.

The last review I did for a Questyle product was the M15 in 2022. That model was eventually followed by the M15i, which became their most well-received dongle to date, at least as far as I know. If you’re curious, their entire product line-up is available on their English website and official shop.

Questyle M18i

As of writing this review, the portable series includes four current models: the M12i, M15i, M18i, and the CMA18P. The M18i brings Bluetooth functionality from the flagship CMA18P into the M-series, and for the first time in this line-up, Questyle has integrated a battery into the design.

For the M18i, Questyle used dual ESS ES9219Q DAC chips in a dual-mono setup. They paired these with four SiP modules built on their patented Current Mode Amplification technology. The internal structure follows what they call TTA, or Three-Tier Architecture, which consists of a dedicated DAC stage, a preamp section, and a separate output stage.

By separating the DAC, preamp, and HP amplification stages, Questyle aims to achieve tighter control over the signal. The four SiP modules are responsible for the current-mode amplification and are positioned to handle both positive and negative phases of each channel independently. In theory, this improves overall performance, especially for balanced output.

If you look at the signal flow diagram, it becomes clear why Questyle chose this layout/arch.

The M18i is clearly built as a balanced-first device, as Questyle doesn’t even provide detailed power specs for the unbalanced side. Personally, I switched to 4.4 mm a couple of years ago, and the M18i delivers a solid amount of power through its balanced output. The 3.5 mm single-ended port is still there for convenience, but it’s definitely not the focus.

Gain is adjustable, and in high-gain mode, the 4.4 mm output delivers 260 mW into 32 ohms and 28 mW into 300 ohms.

M18i is also the first M-series dongle with a built-in battery. In mobile or Bluetooth mode, it runs entirely off its own power instead of drawing from the connected source. The battery is relatively small at 500mAh, offering around 2 to 3 hours of use before depletion. I was honestly blindsided by this design choice, especially considering the device supports LDAC and delivers excellent Bluetooth performance.

In PC mode, the M18i powers itself and charges the battery at the same time, using a dynamic power management system that adapts in real-time to USB current limits and system load.

The M18i is priced at $399 USD, but it’s available for $349 through Questyle’s online store as an introductory offer. The drivers can be found here.

Accessories & Packaging

The M18i comes in a compact drawer-style box that I found quite chic. The packaging is simple but well thought out; you pull on the fabric tab, and the inner tray slides out, revealing the device, some documentation, a USB-C to USB-C cable, and a USB-A to USB-C adapter. Unfortunately, there’s no Lightning cable in the box.

Given the asking price, the accessory set feels a little light. At the very least, a leather case could have been bundled in. Instead, it’s sold separately for 29 USD. The USB-C cable is well-built with a fabric sheath and solid connectors, but it’s a bit stiff and not the most practical for portable use. Overall, the accessories fall short of expectations, especially considering the premium pricing.

Design & Build Quality

The Questyle M18i follows the established design language and form factor of the company’s M-series dongle DAC/AMPs. The first thing that stands out is its matte black chassis, CNC-machined from tempered aluminum. The front features a tempered glass panel that protects a compact OLED screen, while the back has a clean finish with a Questyle logo.

All control buttons are positioned along one side of the device; certification markings like CE are printed on the opposite panel, where you’ll also find the power delivery port. Speaking of ports, the M18i includes two USB-C inputs: one is strictly for data transmission, while the other handles both data and power. This setup offers flexible connectivity depending on your use case.

The buttons themselves are accentuated with chrome borders, giving the device a more refined look. Tactile feedback is excellent; each button press feels deliberate and precise. From left to right, the controls include a physical mode selector switch, a multifunction gain button, volume down, volume up, and the power button. A single press powers the device on, and pressing it again dims the screen.

You need to press and hold for 3 to 4 seconds, then release to power off the device. If you hold it for more than 10 seconds, it triggers a factory reset instead.

The headphone outputs are located on the end opposite the USB-C connectors. Both the 3.5 mm and 4.4 mm ports are gold-plated for better conductivity and long-term durability.

I really like the M18i’s matte black surface; it has a smooth, electroplated feel that stands out among its dongle peers. It feels premium in the hand, doesn’t attract fingerprints, and has a silky smooth finish that’s surprisingly rare among portable DACs, which usually have more textured or grippy finishes.

The review continues on Page Two, after the click HERE or by using the jump below.

Page 1: Questyle, M18i, Packaging & Accessories, Design & Build Quality

Page 2: Experience, Sound Impressions, Comparison, Last Words