Audio-3D.com has Audio-3D Player HD (iTunes Link) for the iPhone and iPod Touch in the iTunes App Store for FREE (regularly $4.99) for a limited time.

Audio-3D Player HD improves the sound of your music and your headphones! It offers a custom made equalization system adapted to your headphones in order to optimize perfectly the sound quality. It supports most of the popular headphone models, and if they don’t you can request your model at contact@audio-3d.com.