AstoundSound Music player can enhance audio from iOS devices
The AstoundSound Music Player (free with a single in-app purchase option at US$2.99) is an audio 'enhancer' designed to increase the 3D spatial effects that can be enjoyed while listening through headphones, speakers, and in cars.
Play your music through the app, and when you switch on the enhancement you'll notice an increase in volume and a slight increase in spaciousness, especially on headphones. There is also a 'bass lifter' that does just that, increases the low end of the music spectrum slightly, keeping things musical.
The GUI is attractive and easy to use. No help screens are needed. Your album art if preserved, and it rotates in a spherical graphic. The app is ad supported, but for an additional $2.99 you can be ad-free, have a choice of nicely designed skins, and enjoy a wider choice of levels of enhancement.
I listened to a variety of music with Astound Sound (film soundtracks, classical, hard rock and some jazz) with pleasant results. You can switch the processing on and off. When it's off, the volume is much lower, so the enhanced version will always sound better as people will generally respond positively to an increase in levels. This is an old trick I learned as a Hi-Fi salesman back in college. When comparing two systems, the one that is slightly louder will 'win' every time.
When I level-matched I still liked the slight processing better than listening straight through, especially on rock and jazz. On classical, I generally preferred a lack of processing.
The best way to see if the app has an effect you like is to do the free download and give it a try.
The AstoundSound Music Player also has presets for different headphone brands, speaker manufacturers and cars. Those options are pretty limited, but it's good to have choices. My preferred Sennheiser and Beyer headphone models weren't there, but other headsets from those brands were.
There are other audio enhancement apps available, including CanOpener, Auvio EQ (free), the Dirac HD Player ($2.99) and the free AudioPhile app. They're all worth a look.
The AstoundSound Music Player requires iOS 7.1 and is optimized for the iPhone 5. It's universal so you are good to go on any iDevice.
