Bass Reduction in a preamplifier?

I've built a small opamp preamplifier to connect headphone out signals (from an iPod or laptop) to something more suitable for line level. The circuit is a simple non-inverting amplifier using a dual opamp with a gain of about 6. It works very well, but I'm hearing a bit too much bass.

I've heard that many commercial headphone output circuits incorporate some bass boost to make up for the inadequate bass response in earbud-type headphones. This got me thinking--is there a way to gently reduce this bass input, perhaps some type of simple R/C filter on the preamp's input section?

Of course, I have no idea what the circuitry of an iPod's headphone output section, so I'd probably have to tune it by ear...

Any thoughts or ideas would be greatly appreciated.