FiiO K9chat_bubble_outlineFrom real comments

The DAC section consistently impresses listeners across both chip variants. Multiple owners single out the DAC as the standout feature, calling it clean, crisp, and highly resolving compared to pricier competitors like the Gustard X26 Pro or Topping D90. The AKM version is often described as warmer and more musical, while the ESS version is seen as more energetic and technically superior, though several commenters felt the two sound nearly indistinguishable in practice despite spec differences.

Software and connectivity problems undercut an otherwise strong package. Several users report the FiiO Music App is unreliable, with Bluetooth dropping out, filters not working, and RGB lighting requiring app intervention every power-on. One user needed pairing with Equalizer APO every session, and another described Tidal switching issues. These software headaches are seen as a persistent weak point FiiO has not fully resolved.

Reliability concerns appear repeatedly despite strong sound quality. Multiple owners reported real hardware failures, including distortion, one-ear dropouts requiring power cycling, sudden dead units, and intermittent audio dropouts even over optical connections. One user was on their third ESS unit after two failures. While many units run fine for years, the frequency of these complaints suggests inconsistent quality control worth considering before purchase.