I purchased the full app last fall. I used it occasionally until recently. I demoed some better IEMs (Shure, Etymotics, UE900s) and this EQ really destroys the original recordings air and detail. On many of my very well know tracks the EQ changes the sound and really does what it advertises. It can also make different headphones sound like others such as giving the Shures the Etymotic sound signature. The main issue I had was when listening to tracks I know intimately even though it can has a pleasing effect on some cans that don't sound like you actually want, it just flattens out the sound and it becomes lifeless. You lose alot of air and spaciousness.
If you read what Golden Ears is trying to do with this app you get a better understanding. They state they are trying to help people that do not want to spend alot of money on a high end headphone get a similar sound. They are also trying to help people tame issues with lower end headphones.
This is a very good EQ but it has its drawbacks. I ended up deleting a $6 app because after making my comparisons across my headphones, I could really hear the bad effects. Even my $99 Shure SE215s just lose to much resolution with the app engaged.
I know this is an old post, but it illustrates a couple of things that I think people need to know about otherwise the accudio app and other similar apps are going to get a bad rap for bad reasons.
Disclaimer: I have nothing to do with any of these apps, I'm just an equalisation nut (see my name).
A lot of headphones, including the Etymotics and the Shures, have a hump at between 2000 and 3000 Hz. That hump is based on the diffuse field theory of headphones. It results in heapdhones that are said to be detailed, and maybe airy. In addition it's a great help to those with hearing damage, and that's a lot of people these days. It's in that region that hearing damage tends to be worst.
But for normal users with normal hearing, those humps make for a compromised audio experience. Listen to etymotics without that hump, for example, and it's stunning the sudden appearance of richness and depth, compared to the thin but 'detailed' sound of the unequalised etymotics. Recent research also strongly suggests that the diffuse field theory is a mistake (vs free field). In other words, etymotics are not really neutral.
Now, what is Accudio up to? I don't know for sure, but I would expect that they are taking out humps at the very least. You should be getting much more accurate audio, but if your ears and tastes (or hearing damage) are tuned to the Shure and Etymotic humps then it may take a while to get used to the new sound, and the loss of so-called 'detail'. In fact, in theory they should be more detailed since the hump won't be covering up the regions just above and below it. Plus you'll have more bass and better treble.
But that's not the end of the story. As you may know from loudness curves, human hearing changes depending on volume. The louder you get the more sensitive to bass and treble. This means that one needs to make a personal treble and bass adjustment according to one's volume preference; some people are loud listeners, some quiet listeners. If you don't do this, and just accept what you're given, the bass and treble won't be where they should be. And you won't be as happy as you could be. It's very much the case that reviews by loud listeners are not valid for quiet listeners and vice-versa. ijokerl, for exmaples, is a quiet listeners, and his reviews are a disaster for someone like me, a loud listener.
(Caveat: I have read somewhere that Accudio's equalisations level out the treble instead of a smooth downward slope, which doesn't work for earphones and will result in far too much treble. So you may need to make a treble adjustment.).
I can't really vouch for Accudio, because I don;t really know what they are up to, though I have used the app on my brother's iphone to equalise his headphones.
But if you would like to try an equalisation of etymotics according to what I've written above, then try these settings:
130Hz -3.5db q=2.8 bw=0.5
650Hz -4.5db q=2.8 bw=0.5
2900Hz -5db q=1.4 bw=1
Then adjust treble and bass according to taste. It's possibly the need for treble adjustment that is losing you 'air'. the dynamic nature of human hearing beaing what it is, treble and bass adjustment are not really optional.
It's worth doing these two also:
40Hz 3db q=1.4 bw=1, nicely lifts low bass to compensate for etmotics bass slope-off.
8500Hz -8db q=4.8 bw=0.3 -- this one is my ear canal resonance. Best to use a sine-sweep to find your own.
