Use a headphone amp
The headphone amplification circuitry included in a typical source or amplifier tends to be basic, and rarely offers the sonic transparency of the other outputs. Dedicated headphone amps take greater care, and have the electrical characteristics required to get the best sound.
An MP3 file will save storage space on your portable player, but a compressed music track is a blight on a sound quality. If you have the space, opt for FLAC or a hi-res download (for example Technics Tracks). You’ll be letting your music collection of its leash.
Shut down background apps
Having other apps running in the background can affect performance if you’re using an Android or Apple smartphone as a source. Close everything down (and shut those pesky notifications off) so your music can run uninterrupted.
Ditch those headphones
Consider getting another pair instead of opting for free headphones as they may not bring the best out of your music. AKG’S Y50s are a good choice, offering a clear, dynamic and punchy performance for £50 (or less).