Mossberg has an interesting review of the new Even earbuds. These are active, in that they have their own battery, and so do some interesting A/D work and calibration for your specific ears.
While younger people may not find this very interesting, I find that I have to turn my music up to ridiculous volumes to be able to hear the detail I was able to hear when younger. (I guess that's the price I pay for having seen Motorhead live!)
My right and left ear are very different nowadays, so this is $99 I am happy to throw at testing these things out. I'll let y'all know what they are like.
Oh... and kleinbl00, I'd love your input, being an audio engineer and all.
I was actually preliminarily involved in building a box that would do effectively this.
Thing of it is, the equal loudness contours are an average, and you do experience significant roll-off with age (regardless of Motorhead concerts). Putting in a DSP that allows you to balance your headphones is a no-brainer; it's astonishing that nobody has bothered to build it yet.
Curious to hear your thoughts.