Muse HiFi has announced its latest portable audio gadget, the M6 Double, a compact DAC and headphone amp that brings together vintage tube tech and modern digital audio hardware in a rather eye-catching package. It officially launches on October 27, priced at $399.99, and will be available in extremely limited quantities — just 1,000 units worldwide — due to the scarcity of its specialized components.

The M6 Double gets its name from the two very different types of tubes built into the unit, one for audio and one for visuals.

First, there’s the JAN6418 miniature vacuum tube, a military-spec component used for audio amplification. These tubes are known for adding warmth and smoothness to the sound — think softer treble, fuller mids, and a more relaxed overall presentation. Whether you’re listening to vocals or acoustic instruments, the goal here is to recreate a listening experience that leans into the classic tube amp character.

But Muse HiFi didn’t stop there. Sitting right next to the screen is a glowing throwback: a pair of Nixie IN-7 tubes. These vintage display tubes, popularized in the 1950s, light up to show your active volume level — not on an LCD, but in glowing orange numerals shaped from wire. Each tube is filled with a low-pressure gas that glows when charged, offering a retro-inspired visual interface that looks like it could’ve come off an old lab instrument. According to the company, this is the smallest Nixie tube display ever used in a device of this kind.

Despite the throwback looks, the M6 Double is loaded with modern internals. At the heart of the digital processing section is ESS’s ES9039 DAC chip — a high-end digital-to-analog converter capable of handling high-resolution PCM and DSD formats with very low distortion and high dynamic range.

To keep things timed perfectly, Muse HiFi uses a pair of Accusilicon AS318B oscillators, one for 44.1kHz family sample rates and one for 48kHz family, which helps reduce jitter and improve clarity. If you’re the type of listener who likes to tweak their sound, the M6 Double includes seven selectable digital filters so you can fine-tune the audio to your preference.

There’s also Bluetooth built in. The M6 Double uses Qualcomm’s QCC5125 chip to offer Bluetooth 5.2 support with hi-res codecs like LDAC and AptX Adaptive. That means you can stream wirelessly from your phone or laptop without totally giving up audio quality.

To run all of this — especially the dual tube systems — the M6 Double includes a specially designed power architecture. The JAN6418 tubes need 25V, while the Nixie tubes require a hefty 170V to glow properly. An onboard microcontroller manages 20 MOSFET drivers to safely and efficiently handle power delivery throughout the system.

The built-in 4500mAh battery is fairly large for a portable DAC/amp, and should provide a decent amount of listening time, though Muse HiFi hasn’t specified exact battery life. Given the extra demands from the tubes, particularly the high-voltage Nixie displays, battery performance will likely vary depending on how you use it.

The M6 Double is a bit of a curveball in the portable audio world. It’s not just another small DAC/amp with a slick display and a metal chassis. It’s a niche device with one foot in the 1950s and one foot in the hi-res audio age — glowing tubes and all.

For listeners who appreciate a bit of vintage flair alongside modern functionality, or just want something a little different in their portable setup, the M6 Double stands out — quite literally, thanks to its bright orange Nixie numerals. Whether you buy it for the sound or the display (or both), there’s no question it’s aiming to offer a listening experience with character.

The Muse HiFi M6 Double will be available starting October 27 for $399.99, sold through HiFi Go. Only 1,000 units will be produced globally, largely because the JAN6418 and IN-7 Nixie tubes are in limited supply. That scarcity, combined with its unique design, likely makes this device more appealing to hobbyists and audio collectors than the average Bluetooth DAC shopper.