Phatlab Rio Review

Phatlab Rio review featured

In this article, I’m checking out the Phatlab Rio high-performance USB DAC/AMP. The Rio features an ES9281AC Pro DAC chip plus an enhanced power supply and smart switch. The price is $238.

Disclaimer: This sample was provided by Phatlab for an honest review. All observations and opinions here are my own based on my experience with the product.

Phatlab Rio Review
The Phatlab Rio blends desktop-grade audio quality and portability in one great-sounding device.
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Clarity and precision
Immersive Soundstage with Precise Instrument Separation
Balanced, Natural Sound Signature for True Audio Enthusiasts
Hardware-level volume adjustment
Suitable for desktop and on the go use
Larger than average for a dongle
Our Score

Phatlab Rio

Box front


In the realm of USB dongle DACs, the Phatlab Rio emerges as a beacon of innovation, transcending the limitations that have plagued its predecessors. Drawing from the triumphs of their previous project, the formidable RASA amplifier, Phatlab embarked on a mission to redefine what’s achievable within the confines of a USB dongle. Their secret weapon? The ES9281AC Pro DAC chip, a powerhouse of audio fidelity. Through meticulous research and experimentation, Phatlab’s engineers crafted a topology that grants the Rio the astonishing dynamics and transients typically reserved for bulkier desktop amplifiers.

Rio upright

Design and Build

Crafted from a solid block of aluminium using precision CNC milling, the Rio’s chassis is rigid and durable. The elegant exterior is accentuated by a tempered glass panel on the underside, adding a touch of sophistication. The top surface boasts a distinctive etched diagonal pattern and model name alongside a discreet LED indicator.

Dynamic LED Indicator

While LED indicators are commonplace in DACs, Rio’s LED brings a unique twist. It mirrors the sample rate being played, shining a magenta hue when playing MQA files. Beyond that, the LED adapts its colour as you adjust the volume, providing a visual representation of the volume level.

USB ports on the Phatlab Rio

Hardware Volume Control

The Rio takes user control seriously with its onboard volume adjustment, operating at the hardware level. This means your volume adjustments won’t interfere with the source device’s output level, allowing you to fine-tune the audio output to your preference. For audiophiles seeking a pure DAC source, the Rio offers a convenient line-out mode accessible by holding the Vol+ button.

Versatile Connectivity

With its primary USB-C connection, the Rio functions as a USB dongle DAC. However, its secondary USB-C connector takes functionality a step further, delivering enhanced power supply and output capabilities. It seamlessly switches between the alternate power sources without interrupting music playback. Not only can Rio deliver more power with its secondary power connection but it doesn’t drain your phone’s battery.

Headphone output on the Rio

Headphone Outputs

The Rio caters to both single-ended and balanced connections. The 3.5mm single-ended output delivers a clean 1.0 Vrms signal, while the 4.4mm balanced output provides 2.0 Vrms. This power ensures dynamic and engaging audio, regardless of your choice of headphones.


Internally, the Phatlab Rio utilizes an ES9281AC Pro DAC chip for decoding and supports all 32bit/384kHz formats: PCM, DoP, DSD64, DSD128 and MQA. To deliver the best audio quality, Rio uses high-capacity conductive polymer tantalum capacitors for maximum dynamics. In addition, it uses larger resistors which run cooler and generate less noise. The added circuit stability ensures the best audio quality.

Phatlab Rio with iPhone


The heartbeat of any DAC lies in its sound quality, and the Phatlab Rio beats with a vigour that defies its diminutive size. The integration of the ES9281AC Pro DAC chip unveils a sonic landscape of clarity and precision.

From the gentlest piano keystrokes to the thunderous crescendos of orchestral swells, the Rio reproduces every nuance with a finesse that belies its form factor. The dynamics are nothing short of excellent, rivalling even some desktop amplifiers on the market. It’s a symphony of sonic excellence, delivered straight to your ears.

But the true litmus test of any audio equipment lies in real-world scenarios. Picture this: You’re huddled in a bustling coffee shop, seeking refuge in your music. The combination of the Rio and your earphones effortlessly cuts through the ambient noise, revealing layers of detail previously obscured.

The impact is immediate; your favourite tracks come alive with an intensity that commands attention. This dongle DAC is not just an accessory; it’s a game-changer for the mobile audiophile, transforming everyday environments into private concert halls.

Phatlab Rio with iPhone and FiiO FT3


FiiO FT3: Nice clean sound with good details. Bass notes are tight with sufficient sub-bass rumble. The midrange is nuanced and emotive with vocals and instruments coming to the forefront. The treble is detailed and airy with good extension up top. In terms of power output, I find it sufficient for the FT3 but it’s pushing the Rio to its capacity. I’d say these headphones are about the limit of what you can use optimally with this device.

Westone MACH 60: Lush, smooth sound with excellent resolution. Instrument separation is excellent and the imaging is precise. The bass is very controlled and has an accurate tone. Mids are rich but spacious, organic and natural sounding. Vocals are super engaging with this combo. The treble is smooth as butter yet spacious and airy. I’d be happy to sit and listen to this pairing all day long.

When it comes to power output, Rio has more than you’d ever need for this pairing. But what sets Rio apart from lesser dongles is its effortlessness, transients and dynamics which are clearly highlighted when paired with an IEM of the MACH 60’s calibre.

Phatlab Rio in action


In the Phatlab Rio, we witness a convergence of technical prowess and unwavering dedication to audio excellence. This dongle DAC isn’t just a gadget; it’s a testament to what’s achievable when innovation meets passion. If you demand nothing short of desktop-grade performance in a portable package, the Phatlab Rio stands ready to deliver.

Input1st USB C (device)
2nd USB C (5V power only)
Output power (4.4φ)2.0 Vrms
Output power (3.5φ)1.0 Vrms
Headphone impedance16 – 600 ohm
Audio formatsPCM: up to 384 kHz
MQA renderer: up to 384 kHz
DSD: 64/128 DoP
Power supply5V/1A
Dimensions (WxHxL)85 x 15.2 x 32.5  mm
Net weight57 grams

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