"Likely clipping", you'd know.
I do +12 at 31hz, +9db at 8khz, -5dB gain. Even with say +9 at 31hz and +7 at 8khz, on all of my IEMs and headphones what they all have in common is that none of them distort at -5 gain, sometimes -3, 0db if it doesn't have bass, depends on the track.