Just curious. I've always used it whether it's on my stereo system, home theater system, or headphone system.
What's with the hate/dislike of equalization in general.
The whole idea where all this stems from is that the equipment themselves must have the flattest response, and that includes for example your room not getting in the way of music by introducing room modes (that kill or enhance bass for example, which either way is not "natural" sound). In my car for example once the installation was done right (tweeters in custom angled pods, door mounts lined with Dynamat, etc) and the processor is set to the correct time alignment* and gain** settings there is really no need for EQ unless I'm competing in EMMA or IASCA, where even tiny bumps really need to be ironed out, but of course an RTA would be necessary to detect them using a sine sweep. Prior to this I had a processor that only had basic settings for these and I relied more on the EQ, which can't fix the fact that the cabin was the problem (I sat off to one side) and the installation sucked (cancellation in the door mounts due to no isolation between the front and rear of the midwoofer cone, tweeters' sound bouncing off the windshield, etc).
In a home audio set-up it's a similar thing, except of course you don't need a time alignment processor unless it's an HT system in a living room where you're not smack in center of the front and center speakers vs the surrounds,
but the room can present its own problems. In this instance, instead of EQ-ing a signal, one must "treat" and "tweak" the room, for example so it does not add or subtract to the bass. EQ-ing the signal only reduces adds or reduces the bass frequencies coming out of the speaker, but even if you can get it down to a level where teh room-amplified (positively or negatively) response is flat on a test tone, the reflections can still make for muddy bass, much like EQ-ing a tweeter to death in a car can't do anything about the sibilance caused by reflections on the windshield to to an improperly-installed tweeter. You can have EQ a system too lean at home and still have no definition on the bass lines, or add a lot and still not get a natural-sounding impact on the bass (as is more commonly used, "slam"); or a car system can sound like you have a cheap tube amp in there along with rolled-off tweeters and still get harsh "t's" and "s'" in the song. because you're hearing the same note several times (except the delay is in microseconds so you don't realize that simply with just your ears).
With headphones one would think it's not as problematic, given the room isn't a factor unless you're listening in a noisy environment, but there is one thing that factors into this in place of the room: the ear pads. Worn out and new earpads sound drastically different, and buying brand-new earpads every month just to keep the sound the same just isn't cost-effective. I get around that by rotating two sets of earpads on my HD600, but I also used EQ apps.to make older pads sound close to the newer pads - I simulate "FLAT" on Accudio using old pads, then I disable it when using new pads. The only thing that stopped me from using Accudio is that they haven't updated for iOS7 compatibility and it's buggy as heck right now, and the earpad rotation alleviates the most noticeable response changes.
Basically, think of this as getting to the root of the problem instead of using a patch. Think of a social issue in thee terms: instead of using subsidies and welfare, you neuter people who can't afford to have children, the same way TNR programs are applied to stray cats, except of course arguing over EQ's role isn't likely to end up with either side getting smashed up in a protest.
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Note that in some cases it really isn't so much as a "flat response" for the whole system, but that some people want to be able to enjoy the speakers' response without the room getting in the way. That I can agree with, but personally I'm not a fan of buying one headphone for each music genre I listen to when there are preset EQ settings like "Jazz," "Rock," etc (or you can customize such) for free. If you can do this with speakers, I'll admit I'm envious of your storage space, but even then I don't think I'd want to take speakers off their stands and put another one on it (or push the tower speakers into position) when I switch to another album.
*Unless you have a Maclaren F1, the inherent problem is that one sits closer to the driver side tweeter then midwoofer vs the passenger side tweeter, passenger side midwoofer, and finally the subwoofer that is usually in the trunk unless you have something like a Nissan with a Bose subwoofer on the dashboard; signal processors get around this problem by introducing time-delays on the transducers closer to the driver (or passenger, as they can be biased either way) so soundwaves around at the ears at the same time.
**The problem with using such a processor though is that the crossover will have to be applied as an active circuit (ie, part of the processor), and when it leaves the processor, you send a signal meant for each transducer (in terms of both time delay and frequency range), and sometimes you have for example amplifiers that are too powerful for each tweeter (it's not like they sell monobloc amps for cars) and using different amps are more cluttered than using one multi-channel amplifier. Gain settings on the amps as well as on the processor then deal with efficiency and SPL variance - in my system the processor outputs a -6db signal to the tweeter and the amp channels that receive this signal is set to minimum gain; midrange signal out of the processor is 0db gain and about 11:00 on the amp's gain knob.
