FiiO E06chat_bubble_outlineFrom real comments

It noticeably helps high-impedance and low-output setups. Multiple commenters found the E06 genuinely improved sound on high-impedance headphones and weak-output devices. One detailed explanation noted it helps overcome high output impedance in smartphones, especially Android devices, preserving bass response. Others confirmed strong results with 250 ohm Beyerdynamic DT-770s, a Wii U gamepad with low output, and an Android phone, describing the bass as making headphones 'vibrate like an earthquake.'

Results are inconsistent across headphone types. Not everyone heard a difference. One user tested the amp on Sennheiser HD598 headphones and found 'absolutely no difference,' ultimately returning it, questioning what the appeal was. Another user reported strong bass and clarity in the first week that faded to no mid-range or low-range after two weeks, suggesting inconsistent or degrading performance depending on headphones or unit condition.

Build and usability drew complaints versus the older model. A user who bought the E06 as a backup to an older FiiO amp called it overrated, citing unintuitive buttons, confusing LEDs, and a disappointing built-in EQ compared to the simpler predecessor. They also disliked the built-in rechargeable battery versus swappable AAA batteries. Others reported confusion figuring out charge status or EQ color changes, and one warned of counterfeit units sold through third-party retailers.