EQE is an iOS runtime modification, so it is not restricted to a single app. It works with all of them.

Spotify, SoundCloud, Apple Music, Hype Machine, YouTube, Snapchat, WhatsApp voice memos, you name it. EQE does not discriminate.

EQE is fully parametric, with support for up to 200 simultaneous biquad filters. Here are a few more of its features:

• Frequency response curve
• Manipulate individual channels
• Bell/peak, Lowpass, highpass, bandpass, highshelf, lowshelf, notch filters.
• Changes to audio happens in real-time (unlike a lot of other equalizer apps)
• Lua scriptable to the core (documentation here)
• Classic graphic EQ controls, for those who prefer simplicity over control

EQE also has the ability to remember your playback history, akin to Last.FM's audioscrobbler.

This also works seamlessly with every app. Set it once, and you won't have to think about it again. Keep your playback history private to yourself, or share it online via the live feed.

EQE requires a jailbreak to install. Open Cydia/Zebra, and search "EQE".