Truthear Keyx – L-shaped USB-C DAC/AMP Dongle with CS43131 and Microphone Support

Truthear Keyx – L-shaped USB-C DAC/AMP Dongle with CS43131 and Microphone Support

Truthear Keyx is a plug-and-play USB-C DAC/AMP dongle built around the Cirrus Logic CS43131 – the same chip used in much more expensive standalone units. It takes the standard dongle format and eliminates what breaks first: the cable. The 3.5mm TRRS port is integrated directly into the L-shaped chassis, connecting directly to your phone or PC without any intermediate cables to force or break.

CS43131 – The chip that matters

The Cirrus Logic CS43131 is a high-performance audio SoC with integrated headphone amplifier – it manages both DAC conversion and amplification on a single chip, which is why it’s so effective in compact dongles. In the Keyx, it delivers 122dB of SNR, -107dB of THD+N at 1Vrms into 32Ω (dropping to -112dB at 2Vrms into 600Ω), and an output of at least 50mW into 32Ω. That’s enough to drive sensitive IEMs cleanly and push most portable headphones to useful listening levels. The CS43131 also includes feedback monitoring for headphone detection, which allows the Keyx to support microphone input – something that DACs with chips without this feature can’t do.

Maximum decoding: PCM 384kHz/32bit and DSD256. The frequency response is flat between 20Hz and 20kHz. In practice, the Keyx isn’t a bottleneck for any source you’re likely to use.

L-shaped design – Why it’s better than a cable

Most dongles in this price range connect to your phone via a short, flexible cable. That cable is a stress point – it flexes every time you move, and is usually the first to fail. Keyx eliminates this completely by integrating the 3.5mm port directly into the body of the dongle. The L-shape means that the USB-C connector goes straight into the port and the headphone jack is perpendicular – a naturally ergonomic position whether the phone is in your pocket or resting on a desk.

The construction is multi-injection molded plastic reinforced with an anodized CNC metal shell. It is designed to absorb the mechanical stress that previously went to the cable.

Microphone Support – The Detail That Matters to IEM Users

Most entry-level DAC dongles eliminate the microphone signal. The Keyx uses a 4-pin TRRS output, which means that if your IEM cable ends in TRRS (like most cables with in-line controls), your microphone will pass through. Calls, Discord, voice chat, recording – it all works without the need for a separate microphone or adapter. Keyx also supports online DSP, which means that software equalizers and processing applied at the operating system or app level work correctly without degrading the signal.

Founder’s Take

Keyx answers a question that the IEM community is constantly asking: what is the minimum DAC dongle that really makes a difference without costing more than IEMs? The CS43131 is a genuinely good chip, not a low-budget compromise, just a compact implementation of proven technology. The cable-free L-shaped design is the right decision for a product that will live in a pocket or backpack. Microphone support is the feature that most cheap dongles skip and that most gamers and remote workers actually need.

Whether you’re pairing this with IEMs for gaming or for everyday use on a laptop or cell phone, this is the DAC that does everything you need and nothing you don’t.

⚠️ iOS Note: Requires a Lightning to USB-C or USB-C to USB-C adapter for use with iPhones. Not included.

IN THE BOX

• 1× Truthear Keyx DAC/AMP Dongle