The iEmatch is a purely passive device. It cannot by itself produce distortion. Any distortion observed is from the driving amplifier.
Further question: But I tested mine with an IEM that’s sensitive also, it lowers the volume like an adapter, but it introduces distortion?
Answer: It may be that you used a lot of attenuation and then cranked excessively. The amplifier is likely to distort, this is not uncommon.
