Truthear Keyx – CS43131 L-Shaped USB-C DAC/AMP Dongle with Mic Support

Truthear Keyx – CS43131 L-Shaped USB-C DAC/AMP Dongle with Mic Support

The 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 the one thing that breaks first: the cable. The 3.5mm TRRS port is built directly into the L-shaped chassis, connecting straight to your phone or PC without any intermediate cable to stress or snap.

CS43131 — The Chip That Matters

The Cirrus Logic CS43131 is a high-performance audio SoC with an integrated headphone amplifier — it handles both DAC conversion and amplification in a single chip, which is why it's so effective in compact dongles. In the Keyx, it delivers 122dB SNR, -107dB THD+N at 1Vrms into 32Ω (dropping further 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 is why the Keyx can support microphone input — something DACs using chips without this feature cannot do.

Maximum decoding: PCM 384kHz/32bit and DSD256. Frequency response is flat across 20Hz–20kHz. In practice, this means the Keyx is not 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 attach to your phone via a short, flexible cable. That cable is a stress point — it flexes every time you move, and it's usually the first thing to fail. The Keyx eliminates it entirely by integrating the 3.5mm port directly into the body of the dongle. The L-shape means the USB-C connector goes straight into the port and the headphone jack faces perpendicular — a naturally ergonomic position whether the phone is in a pocket or flat on a desk.

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

Microphone Support — The Detail That Matters for IEM Users

Most budget DAC dongles drop the microphone signal. The Keyx uses a 4-pin TRRS output, which means if your IEM cable is terminated in TRRS (as most cables with in-line remotes are), your microphone goes through. Calls, Discord, voice chat, recording — it all works without needing a separate mic or adapter. The Keyx also supports online DSP, which means software equalizers and processing applied at the OS or app level work correctly without signal degradation.

Founder's Take

The Keyx answers a question the IEM community asks constantly: what's the minimum DAC dongle that actually makes a difference without costing more than the IEMs? The CS43131 is a genuinely good chip — not a budget compromise, just a compact implementation of proven technology. The L-shaped no-cable design is the right call for a product that will live in a pocket or bag. Mic support is the feature most cheap dongles skip and the one most gamers and remote workers actually need.

If you're pairing this with IEMs for gaming or for daily use on a laptop or phone, this is the DAC that does everything it needs to and nothing it doesn't.

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

IN THE PACKAGE

• 1× Truthear Keyx DAC/AMP Dongle