If you've ever wished your portable DAC could do more—like double as a headphone amp, handle pro-level audio formats, and even record analog sources—Questyle’s Sigma Pro will catch your attention. Priced at $999 on Amazon, this all-in-one device is designed to bring desktop-style functionality to a unit about the size of your phone. Whether you’re using in-ear monitors, big over-ear headphones, or patching it into a studio setup, the Sigma Pro tries to be a flexible option that doesn’t stay tied to your desk.

Despite being roughly the size of an iPhone 16 Pro Max and weighing in at about 330g, the Sigma Pro isn’t just a pocket-sized upgrade—it’s meant to be a real tool for serious listening and recording. The case is made from machined aluminum with a see-through glass panel on the front that gives you a look at the internals. It’s more than just a design flourish—everything inside is arranged with purpose.

At the heart of the device are two ESS ES9069 DAC chips, set up in a dual-mono layout. This setup allows it to decode high-res audio formats like PCM up to 768kHz and DSD512, formats usually reserved for much bigger gear. To handle amplification, Questyle includes its Current Mode Amplifier, a patented design built to deliver enough power for anything from sensitive IEMs to 300-ohm headphones.

The Sigma Pro offers a wide range of connections, making it adaptable to most gear. You get:

• 3.5mm single-ended output
• 4.4mm balanced output
• 6.35mm output (full-size headphone jack)
• Optical and coaxial digital inputs
• 3.5mm and 4.4mm analog line inputs

If you prefer wireless listening, it’s covered there too. Bluetooth 5.4 support includes LDAC, aptX Adaptive, aptX HD, and Snapdragon Sound, so you can stream high-res audio from your phone or computer without being tethered by a cable. And for iPhone users, Apple MFi certification means plug-and-play compatibility without adapters or power issues.

The device also has two USB-C ports—one for audio and one for charging—which means you can listen while it charges. It runs on a built-in 4300mAh battery that lasts up to 12 hours, so you won’t need to babysit a charging cable throughout the day.

One of the best features here is something most portable DACs don’t offer: recording support. You can feed analog signals into the device using the 3.5mm or 4.4mm inputs, and it will convert them into digital files that you can store or pass along to a connected computer.

That means it’s not just for playback—it can also be a useful part of a field recording setup, podcast kit, or even a way to archive vinyl or tape audio in high quality. It also supports real-time monitoring, which is helpful when you’re working with microphones or instruments.

According to Questyle, the amplifier inside the Sigma Pro can reach peak output voltages up to 25Vp-p and deliver up to 5A of current, while keeping distortion down to just 0.0002% under load. That translates to a stable signal even when driving demanding headphones.

The design focuses on keeping signal noise low while offering enough headroom to handle dynamic music or complex soundscapes. Whether you're listening to quiet, intimate tracks or something more layered and orchestral, the Sigma Pro aims to reproduce it all with detail intact.

If you like the idea but don’t need the full recording functionality or multiple inputs, there’s a more affordable version called the Sigma, priced at $649 on Amazon. It drops the dual-DAC setup in favor of a single AKM AK4493 chip, and skips the coaxial, optical, and analog inputs. But it still includes the same amplifier architecture and wireless codec support, making it a solid pick for everyday use without the extra bells and whistles.

The Sigma Pro has been tested with all the major platforms—iOS, Android, Windows, macOS, and HarmonyOS. No driver installation is needed for most systems, so you can plug it in and start using it right away.

Whether you’re connecting it to your smartphone, gaming handheld, or home audio setup, the Sigma Pro is designed to slot in without too much setup hassle. And because it can function as either a headphone amp or a line-out DAC, you can easily move between casual listening, critical monitoring, or even studio work.

The Questyle Sigma Pro isn’t trying to be a mass-market gadget. It’s built for people who want a single device that can handle high-res playback, drive various headphones, work as a digital recorder, and connect to just about any audio source. If you find yourself switching between devices or setups throughout your day—or you’re tired of juggling multiple boxes and cables—the Sigma Pro might offer a cleaner, more flexible solution.

It’s not cheap, but it’s clearly not designed to be. For those who want portable gear that behaves like desktop hardware, this is one of the few options that tries to tick all the boxes.