audio-sound @ hatena

An audio review & news blog. The volume should not exceed 80 dB is recommended. I usually adhere to the safe-listening style by WHO. Please note that my aural impressions and interpretations of measurements are also made from a safe-listening style.

(Chi-fi IEM Review) Yu9 U-554: A well-made etymotic clone. An alternative to ER4B. Recommended for vocal songs and ASMR

Yu9 U-554

Yu9 U-554




  • This review is based on a sample provided by Yu9 Audio to convey a sincere quality review to our readers.
  • No remuneration or compensation, such as a manuscript fee, has been received for publishing this, and it is an honest evaluation based on measurement data from personal testing and personal opinion.
  • Please read the privacy policy of this website.


  • People who like near-field sound
  • People who want earphones for vocal songs
  • People who are looking for earphones for ASMR, voice drama, or narration
  • Musicians and performers who want excellent stage monitors
  • Etymotic Research fans


Overview of Yu9 U-554

This review will give an overview of Yu9 U-554. A complete review of this product can be found here.


audio-sound Score

  • Total Score: 8.8 / 10.0
  • Package: 8.5 / 10.0
  • Build quality: 8.5 / 10.0
  • Fitment: 9.5 / 10.0
  • High range: 8.0 / 10.0
  • Mid range: 9.5 / 10.0
  • Low range: 9.0 / 10.0
  • Less distortion: 7.0 / 10.0
  • Cost performance bonus: 11.0 / 10.0


  • Want to see the score ranking? Click here!


Basic Specifications
  • Frequency response: 20Hz to 16kHz
  • Impedance: 88Ω
  • Sensitivity: 113dB/Vrms
  • Cable connector: 0.78mm 2pin



Packaging meets price standard. The outer box is simple, but made of paper and easy to dispose of. The accessories are fairly complete.


Package contents
  • Yu9 U-554
  • Many ear tips
  • Carrying case
  • Cleaning cloth
  • Cleaning tool
  • Cable clip
  • Manual


Build quality

The build quality of the exterior is above the standard of the price range.




The fit and sound insulation are quite excellent. However, it is not at all suitable for those who do not like to put the earpiece deep into the ear.



Sound quality

REW Frequency Response

The measured values this time are shown in a normalized graph based on the measurements at HATS (blue) and a normalized graph closer to the official measurements (green)


Sound quality description

In this review, I use the standard eartips size L and drive it with the FiiO M15.


Yu9 Audio claims that the U-554 is a clone of the Etymotic Research ER4B. In fact, its sound is quite faithful to the Etymotic target, with a midrange-oriented balance.



Please see here for detailed reviews on sound quality.


Sound quality general comment
  • Original Sound Fidelity: S-
  • Recommendation: A-
  • Personal preference: B+


Yu9 U-554 is a clone earphone that can be considered if you want to get an ER4B or ER4SR at a lower price. The fit and usability are superior to the original, and the sound, including characteristics other than frequency response, is made very close to the original. Considering the overall fit and feel, there are some areas where they can be used as upwardly compatible. For example, when used as stage monitors, they are clearly superior to the originals.


However, it may be necessary to take into account that in the same price range there is the ER2SE, which Etymotic positions as the studio monitor of the new era. The ER2SE is also a very good studio monitor in terms of resolution and low distortion.


Sound quality features
  • High original sound fidelity
  • Near-perfect near-field sound
  • Rich harmonics
  • Mild highs
  • Good vocal focus
  • Monitor-like low frequencies
  • Forward localization-like


  • Lacks expandability
  • Lacks low-frequency depth
  • Lacks clarity
  • Upper midrange to upper mid-high range that tends to sound claustrophobic and noisy


Yu9 U-554


General comment

The Yu9 U-554 is a well-made clone of the Etymotic Research ER4B. It has an improved fit, improved usability, and definitely better value for money than the original. The packaging is not cheap either.


Open Audio Alkaid

Yu9 U-554

Yu9 U-554