Quote:
Originally Posted by
Foe-hammer 
I've been looking for the same thing. Ideally the equalizer would be better before the mixamp, as not to distort the DH 5.1. But finding one with an optical in and out will be difficult. Having an equalizer after the mixamp probably would work, but it MIGHT interfere with DH. I'll look into this more and please keep us posted on what you find out.
Formulanerd also wrote “honestly you're probably better off picking a can that has the characteristics you want vs. trying to EQ the sound.”
One of the main reasons for looking to EQ the sound is so that one or two sets of cans can be optimized for my current favorite games and also work well with any future games. The following examples are not precise; however they help explain my desired benefits.
For Modern Warfare 2, most of the time, I would like the opposing team’s footsteps to be heard over air strikes, sentry guns, etc. Sometimes near the end of a match, just let me hear the unsilenced assault rifle in its full glory.
For racing games, I really enjoy the sound of the revving engine.
In some future game, who knows? There may be levels where it is best to add gain to the 500Hz sounds while reducing the gain from the 4000Hz background noise. Other games or levels may swap these so that the enemies can be heard at 4000Hz while the background noise is at 500Hz.
With a graphic equalizer, I could add or reduce gain around the key frequencies. I could even adjust the equalizer within a match or between levels and checkpoints. These adjustments may be less than ideal for music; but they could add enjoyment to some games.
The above helps explain why I am looking at equalizers, below is the reality.
So far my searching has reinforced the comments by formulanerd and foe-hammer. Trying to equalize the toslink dolby digital 5.1 (6 channels to equalize) severely limits my options. I might have found a Krell unit, but do not care to spend over $10,000. I passed over quite a few articles and products that discuss using a PC to equalize the dolby surround signal (I would like to keep my PC out of the process).
There are many more choices for equalizing the output after the DH processing using the astro output. Using headphone lead from the astro y-cable, the signal is now down to 2 channels (left and right) and analog. There are quite a few 2 channel equalizers. However, several people have told me that equalizing dolby headphone signals will mess with their positioning and soundstage.
Here is a link that may discourage you from trying to equalize the dolby surround signal. Look at the tip on the bottom of the page.
http://inethometheaters.net/faq_avreceivers.asp
If I do end up purchasing an equalizer, it will probably be equalizing the Dolby Headphone 2 channel signal. When I turn the equalizer on and adjust the sliders, I will be trading off surround positioning detail for frequency detail.