digital equalizers

Stopped up ears caused by allergies have led me to using the Itunes equalizer. I don't like the sound of the equalizer when my ears are clear, but when they are not, the equalizer and balance control make listening much more enjoyable.

I'm curious though about how (in very general terms) the digital equalizer works. Does it attenuate or boost? And what does it do to the bit stream? And I wonder if it has an effect on bit perfect output?

Also, since I do have some permanent high frequency hearing loss I've often wondered if a really good equalizer would enhance listening, even when my ears are not "plugged up".

Any feedback is much appreciated.

Sounds like you need an equalizer. You can buy an excellent one for only about $350, including calibrated mic. At this price hands-on (and ears on) experience beats any opinions you may get on this site.

Behringer DEQ2496, available through, and many other places.
I was wondering much the same thing, but specifically about the pros and cons of the digital equalizers in media players (e.g., foobar, itunes) and/or other software. Does digital sound processing of this type have any detrimental effects on the data stream and , ultimately, the audio quality? I played with the digital parametric equalizer in some recording software (Ableton Lite) once and found I was able to make adjustments that really improved the sound quality for me. Incidentally, one of the adjustments was to boost the frequencies above 10K a few dB. I have been considering the Behringer Ultracurve EQ option, but am moving toward a PC based system and would like to know if equalization could be dealt with in the media player or possibly with a software plug-in.
Of course there are some who will put down anything digital.

You can put digital in and get it out from the DEQ2496, so that removes concern about A/D and D/A conversion. (By the way they are excellent 24 bit 96KHz devices). The equalization and other processing is accomplished by a 32 bit floating point device, so the only effects on the sound will be the ones you command.

Again I say give it a try with your own ears.
Eldartford and Nosnhoj,
Thanks for your feedback.

I did not know about the DEQ2496. It looks like a good possible solution. I like the general idea of combining a DAC and equalizer.

But in the short run I want learn more about the equalizers included with various media players--esp how they work.

For exaple I notice in Itunes that when I turn on the equalizer the volume goes down and moving the db slider of course brings it back up, but I wonder what is happening to the bit stream as I minipulate these various digital controls.