"It looks like engineering to me. The difference is all measured over at Innerfidelity between the 25 and Amperior, so its not just perception."
I'm sorry but as you are not an engineer of headphones these posts do get tiring. I don't know how to take them. Of course it's perception. You are acting like scribbles on paper can somehow be directly realized in our ears with one glance. Especially, when we have had an uproar over if Tyll's pair was defective or close in that regard. It's pretty obvious from his measurements that either his headphones are mismatched or the readings are not perfect for whatever reason. I have tested my left and right channels as much as anyone on here and I don't hear anywhere near a 2dB difference in sound between mine. In fact, I hear almost none at all with mono recordings.
Similar to: but the timbre on the instruments, the texture in the bass, the natural and polished sound of the Senns just sounds more true than the 1350s.
This is not an affront in any way. I just see this for every great headphone ever on Head-fi. It makes me cringe slightly. On what music with what setup? It's too hard to say this about anything. I like the sound of my car better than headphones but if I were to say the texture of the bass is better I don't think anybody knows what the heck I am talking about. What kinds of textures? I happen to feel the texture of the bass is tight and defined quite well on the DTs especially in sub regions where it does remind me of a mini sub. It simply grabs me like few headphones do but then again this could be because of the amp and headroom where as portable you might not hear it as much.
Being a true basshead who sends over 1k watts to an IDMAX I yearn for that feeling in headphones and rarely find it in this range. The Amperior certainly does not have it.
What about the midbass hump in the Amperiors? Does that factor into the texture of the bass? What about the low end bass in bass guitars and kick drums?
Natural and polished sounds means so many things to so many people that frankly I have given up trying to pinpoint what natural means anymore. That is not to say your post is without merit. You could say that upper midrange is near perfect on the Amperiors or something. Is there something missing there on the Beyer? Again, I am not really sure as it depends on the music I am listening to. They can sound a bit off at times but I expect that from any 300 dollar headphone. In fact I expect worse lol.
And let's for a second act like Tyll's measurements are just what they are: one guy's measurements. I for one don't hear this huge sound difference but then again I am not amping these with some crappy little portable amp either (not that Tyll is). I think it is all in the eye of the beholder really. If you are going to amp with tiny portables or you are not going to amp at all then the Amperior might be the way for you.
On the other hand aluminum or not I think they are ugly as hell and prefer vocals and lean tight bass all the way down to the subfrequencies more than most. I will give the Amperiors another listen but at 18 ohm I don't really feel like I need to take them home and hook them up to the Denon. I thought they sounded good but I won't be replacing my DTs for that especially when its 350.
It seems the price war has started. I expect the 400 class to appear soon lol. The fact the materials in these things cost soooo much less than that is still a bit disturbing to me. I guess the engineers are paid well.
I don't think you need to apologize for laying anything out on the line. We have had plenty of discussion on this board that went way beyond that into the nether regions.
I have not been too concerned with the cord. Most manufacturers do not skimp on the cord I would like to know what Beyer uses in it. As in if there is any silver or what kind of copper it is. Sometimes I am not sure if people are getting entirely different Beyers as we were talking about before hahahaha.
Also no offense but I don't particularly like supporting Apple. I will have to drive by and bring some decent music to listen to again that I know well. But as I said last time it did not go well and that is why I wanted to see how they sound on the Denon. 18 ohm though, geesh, I can't believe much is going to change because not much changes with my Etymotics and they are near 30 ohms or whatever. Factor in the top level you can push the Beyers to and I just don't think I will be replacing mine.
"The pads on the Amperiors did seem to let more sound through which means the 25s most likely have an edge."
There is no question in my mind which one wins out here. The DTs simply isolated far better than the Amps Apple had laid out for all to use. I have no idea how many people tried them on though. And there is no way to bend the metal slightly without destroying them to make them isolate any better. I for one do not like Amp pads at all. That is not to say the DTs are perfect as they can get uncomfortable with long sessions.
but I couldn't help noticing the cable is pretty thin. I'm not concerned with an improved sound quality but more the durability. 
