Moondrop CHU II High Performance Dynamic Driver IEMs Interchangeable Cable in-Ear Headphone – Sold by SHENZHENAUDIO UK STORE / FBA

Apparently these come close to the quality of those costing over a grand.
Aluminum-Magnesium Alloy Dome Composite Diaphragm As a dome diaphragm material, AI-Mg alloy exhibits high rigidity and light weight, thereby extending the treble bandwidth and revealing more subtle details. The diaphragm suspension is composed of two polymer materials with differing characteristics,resulting in a punchier bass and greatly reduced nonlinear distortion.
Alloy Casting Cavity Ensuring Durability and High-Quality Texture The acoustic cavity of theCHU IIis manufactured using MOONDROPs mature alloy casting technology, ensuring both rigidity and fine texture. A durable paint layer protects the metal shell from corrosion.
Brass CNC Acoustic Nozzle The nozzle of the CHU II consists of a separate brass CNC component, offering higher precision and density, and resulting in beautiful timbre.
Replaceable Acoustic Nozzle CHU II incorporates a new generation of replaceable acoustic filters. The front end of the brass nozzle is detachable, allowing users to replace the acoustic filter quickly and conveniently.
Ultra-low Nonlinear Distortion Reproduction of Subtle Details Thanks to the solid technology and meticulous design of the diaphragm material, CHU IIoffers a nonlinear flll frequency distortion below 0.05%resulting in natural timbre and the reproduction of even the sublest details.