Disclaimer: This IEM is owned by a friend of mine.
Phiaton is a high-end brand of South Korean company, Cresyn, which was formerly known as Leemax. As they have been manufacturing OEM products for Panasonic, Audio Technica, and many other well-known companies for a very long time, they must be well-aware of what they're doing.
...Or are they?
CON: Short bandwidth. Although the left unit is slightly faulty; this must be an isolated case.