Once upon a time, any audiophile worth his salt owned (or at least wanted) one of these beasts. The thought being that a graphic equalizer allowed control over the entire audio spectrum instead of just at the ends, as the more common bass and treble controls afforded. In theory it allowed you to tweak specific ranges of frequencies to achieve the desired "flat" (i.e. uncolored) response from your audio source. Alternately, you could use the equalizer to boost or reduce frequencies intentionally for effect.
It wasn't until the early 2000s that I actually had an equalizer in my system, although not nearly as impressive as the one above. And you know, I found it to be a complete waste of money. Maybe it was my already-aging ears deceiving me, but I found nothing really needed a degree of tweaking that couldn't be accomplished with the bass and treble controls on my receiver.
Funny, that.
Anyhow, I was thinking the other night how I wish there was some sort of equalizer for life; something that allowed you to fine tune those areas that needed a little help. Increase employment or employment satisfaction, boost income, decrease fear and anxiety.
Sadly, no such device exists, not even in the darkest recesses of eBay.