Yu9 is not a factory.
It is one person.

It began in 2017

The story began in 2017. Starting from DIY, the founder took on a monument in the history of in-ear monitors: the Etymotic ER4. The ER4 is known for its nearly flat frequency response, a lifelike balance across lows, mids and highs, and close to ideal point-source behavior. For countless veteran listeners it is the very definition of "accurate".

Yu9 deeply shared this pursuit of the real. Beyond recreating the ER4's sound faithfully, Yu9 quietly solved its notoriously difficult fit with an over-ear shell, bringing that purity to many more ears. When veteran listeners put on these recreations, the feeling of something both familiar and new spread the name "Yu9" quickly through the community.

The obsession of an old-school DIY audiophile

People who know Yu9 often mention a particular old-school DIY obsession: fussiness over solder joints, deep study of driver matching, and a stubbornness that runs against spec wars and marketing gimmicks. Yu9 has no intention of growing the brand big, does not pile up numbers on paper, and simply works on every unit until satisfied. Yu9 even writes ear tip pairing recommendations personally, so every listener can hear each design at its best.

The care goes beyond the earphones themselves. From upgraded 7N single-crystal copper cables and fully oxygen-free copper connectors to 4.4mm balanced plugs precision-machined by CNC from Japanese stainless steel, Yu9 handles every step personally. Yu9 is a rare hand-builder who studies everything, from drivers to cables, from tuning to connectors.

Que: from recreation to original

All of this comes together in the flagship in-ear monitor Que. The name comes from the tall, precise towers of classical Chinese architecture, echoing Yu9's pursuit of acoustic structure. With 1 dynamic driver plus 3 balanced armatures and a precise four-way crossover, it brings separation and detail close to flagship level at a far lower price. Several international reviews have called it "beyond its class", a "giant killer" and the top pick under $500, proving one thing: a small maker can take a seat at the flagship table.

In 2026, the feedback gathered after Que's launch led to the limited Merqury: the body is unchanged, with an uncoated CNC faceplate, a four-strand cable and re-matched ear tips, 399 units worldwide.

Why Soundessence

We are Soundessence Ltd. (成音貿易有限公司, company number 60624259), the Yu9 distributor in Taiwan. In an age that values speed and scale, a pure hand-builder like this deserves to be heard by more headphone lovers.

For orders shipped outside Taiwan, we handle everything ourselves from Taiwan: a 12-month warranty, where you ship the unit to us and we pay the return shipping. Earphones like these should not be judged by specs alone. If you are unsure, talk to us on LINE or email server@soundessence.com.tw.