How to increase headphone loudness beyond 100%? I am very hard of hearing.

Is there a sound amplification app one can use with earbuds? Earbuds with a microphone for a Droid are a non-issue but I don't know where to find an inexpensive app to work with the hardware.
If you have one of the supported phone models:

There's an app called voodoo sound.


Voodoo Sound in Google's Play store
Downside: Requires a custom kernel, only for supported phones (see description in market)


The paid app comes without a requirement for a custom kernel (but needs root)


Voodoo Sound Plus


Both replace the audio codec's driver and allow fine tuning and to turn on formerly unused chip features (see description).