iEQ

Fine-tune the tracks in your music library. In your headphones or any speaker system, anywhere.
iEQ is a ten-band graphic equalizer for iOS that provides clean, transparent equalization through ten two-pole cascaded bi-quad IIR filters, centered at sonically and musically useful frequencies.
After opening iEQ, simply select the song, playlist, audio-book etc. from your Music Library, Device Files, or iCloud Drive, hit play, and move the sliders up or down until you like what you hear. The Attenuation slider on the left lets you control the overall volume and helps keeps the sound from distorting (NOTE: since the ten frequency cut/boost controls may be used to add more gain to a track already be close to "clipping", it's possible to create distortion with your EQ settings. If this occurs, remove the distortion by lowering the overall signal level with the attenuation control).
Use the On/Off switch to compare between the original sound and your EQ’d settings.
iEQ your will help your music sound its best, anywhere.