All inspiration began with our fascination for the IN-12 Nixie tube.

Our first experiment involved using the IN-12 in a portable DAC/AMP, and that sparked a bold idea: Could a smaller, more refined Nixie tube be integrated into a portable device?

After extensive research, the team’s focus converged on the IN-17, the smallest Nixie tube ever made.

Since its invention in the 1950s, the Nixie tube has been widely used in aerospace controllers, Wall Street stock displays, and nuclear power plant instruments. While the industry typically employs larger tubes like the IN-12, the IN-17 is exceedingly rare and holds significant collectible value.

For the M6 Double, the MUSE HiFi team spent 12 months collecting over 2,200 IN-17 tubes across Europe, starting from Russia. Of these, 2,100 units were reserved for production, and 100 units kept as after-sales spares.

Research indicates that this batch represents virtually the last usable IN-17 stock worldwide, making MUSE HiFi the largest single holder of IN-17 tubes in the world.

The M6 Double is the world’s first portable Bluetooth DAC/AMP to combine the JAN6418 vacuum tube, produced by Raytheon (USA) in 1974, with the IN-17 Nixie tube, crafted in the Soviet Union during the 1960s.

It stands not only as a technological innovation, but also as a tribute to classic electronic craftsmanship.

From day one, there was no reference or precedent for this design. The definition of the M6 Double was extraordinary — and the challenges faced during development went far beyond typical technical obstacles.

At first, only about 200 IN-17 tubes could be sourced within China, which was far from sufficient for production. The team then expanded its search overseas, scouring multiple countries for the remaining tubes.

After numerous setbacks and moments of near-abandonment, we finally secured enough IN-17s for full production, even accounting for losses during R&D testing.

Even now, we continue to seek out IN-17s and explore other types of vintage vacuum and Nixie tubes, hoping to integrate them into future products.

This spirit defines the essence of the M Series, a relentless pursuit of innovation and craftsmanship, blending rare electronic components with modern Hi-Fi technology to create timeless works of art.