I have arrived with my impressions so far. They're both in Cherry by the way.
Eikon
The very first thing that becomes very apparent when you put these headphones on is the fact that they're not the usual ZMF Headphone. They are supremely neutral. That is, nothing actually stands out in the frequency range (which will be a good thing for most people.) In fact, the only two things that seem to be emphasized is the tiny bit of darkness and the tiny bit of subbass emphasis. The best way to put it would be: "It presents music very, very well, and that's that."
The big, big thing about this headphone is the resolve and transients. It is incredibly ******* fast, incredibly ******* detailed, and incredibly ******* clear. Everything this headphone does is well textured (especially the bass.) Hell, I'd say the bass outdoes the Fostex biocellulose headphones in texture and detail. Maybe not impact, but that isn't something everyone wants in the first place (as everything gets sacrificed.)
I'm keeping this short, as I'm more wanting to get my impressions in order before I say much more. But, the big take away here is that Zach took a biocellulose driver, and made it neutral without losing any of the benefits. Because of that, we end having a headphone that makes the TH900 look like a mistake. Hell, even outdoes it in soundstage (though, I still wouldn't say the Eikon has a large soundstage.)
Atticus
Did you want the Omni, but obviously heard it being held back by the T50 driver? Did you wonder where the lower mids went? Well...guess what? They went into the Atticus. (Side-note, I am going into a bit more detail with this one becuase there is a weird lack of them going around.)
Seriously though, if you wanted a headphone with the same quality as the Eikon, but with the ZMF House sound, this is the headphone for you. While the transients are slower (as the decay is a bit more natural to my ear,) the Atticus is every bit as good as the Eikon (just different.) That includes the superb resolve.
The mids and bass are very much a focus of this headphone. The vocals sound amazing and acoustic guitars sound exemplary with this bad boy. The decay and texture in this region is a bit more obvious over the Eikon (as the decay is slightly slower and the mids are a bit elevated.) This includes the upper-mids.
The bass, on the other hand, actually reminds me more of the THX00 and the Fostex stuff than the Eikon does. The Atticus has a healthy amount (not too much) of midbass and subbass that oddly stays incredibly clear and textured (meaning it lacks a lot of distortion in that area.)
If you're a treblehead, you won't like this headphone. But, if you're not, the treble is very well done, and there's a surprising amount of air to it. That said, I would actually place the Eikon's treble a bit ahead of the Atticus. At the same time though, the treble is not meant to be the focus here...it does its job well and doesn't make me feel like it is lacking in anyway.
The only issue I have the Atticus is that the soundstage is incredibly wide and occasionally makes things sound distant. I have this issue more in games than actual music.
Now, I have to come clean with something...the Atticus I'm listening to is different from the rest. It actually has a slightly upgraded driver (The magnets are bigger/membrane material stiffer.) This removes the issue of muddiness that some people have heard in the bass of the Atticus. That, and it's the production driver (as in, this is what is going into the Atticus' being created.)
That all said...I'm preferring the Atticus overall at the moment. I may be in the minority, as I know most people here would love the neutrality of the Eikon.
