Custom, but entirely flat equalizer sounding different from no equalizer?

[SwordAngel]

I have a 1st gen FiiO X5 with the last official firmware update (I know it's OOOOOLD, but please bear with me).

Today was the first day I try to fiddle with the equalizer in the FiiO X5 at all, after all these years of owning it.

To my surprise, when I set the equalizer to "Custom", but with all the bands completely flat at 0 db, it sounds different from the "Off" setting. The "Custom", but flat equalizer sounds more muffled, whereas the "Off" setting definitely sounds clearer.

Is this a software or hardware bug? Is it a common problem in certain brands/series of DAPs or certain DAC chips or whatever?

 

[megabigeye]

I used to use the original X5, too. I used the EQ often and it always threw me whenever I'd turn it on. Always sounded muffled.

Turning on the EQ applies negative gain in order to avoid clipping. It's just lowering the volume by 6 decibels (if I recall), which sounds muffled in comparison to having EQ off. I.E., louder always sounds better/clearer than softer, and having the EQ off is 6dB louder than having it on.
The annoying part for me was that the EQ always sounded muffled, even after I'd turn the volume up... Unless I managed to forget that it was on, in which case I realized it actually sounded fine.

To use that EQ, adjust every band to the max setting, and then make cuts from there. E.G., if you want a 3dB bass boost, adjust the bass frequencies to max (+6dB), and adjust all frequencies you don't want boosted to 3dB below that (+3dB).

 

[goodvibes]

I have a 1st gen FiiO X5 with the last official firmware update (I know it's OOOOOLD, but please bear with me).

Today was the first day I try to fiddle with the equalizer in the FiiO X5 at all, after all these years of owning it.

To my surprise, when I set the equalizer to "Custom", but with all the bands completely flat at 0 db, it sounds different from the "Off" setting. The "Custom", but flat equalizer sounds more muffled, whereas the "Off" setting definitely sounds clearer.

Is this a software or hardware bug? Is it a common problem in certain brands/series of DAPs or certain DAC chips or whatever?

It's not uncommon at all though the amount of fluctuation will vary from barely noticeable to quite noticeable depending on how resolved the DAP and or headphones are. I know some will have issue with that but so be it.