Here are some quick impressions: this is using the a Burson DA-160 DAC, Violectric V100 AMP and an iPhone 6. I listened the Elder Scrolls: Morrowind OST, Halo OST, Lazerhawk, Cannibal Ox: Cold Vein and Radiohead: In Rainbows.
First off, I can't stress enough how well this headphone is built AND how comfy it sits on my head. My headband is on 5, so I can see these headphones fitting most people's heads. The pads feel like pillows against my ears and the weight distribution is fantastic. The box it came in is very nice, although I think that it's a bit over-the-top in weight. The cables are wonderful as well. They do not have kinks and kind of drape over everything, or conform to whatever surface they are lying on.
These headphones have a unique sound signature, and I believe that this is what the Fostex TH-900 should have been. This is a tasteful V-shape sound signature, maybe more of a U-shape even. I think this is the only headphone that I've owned that gets close to the quality of the TH-900's bass and I own the TR-X00. The Z1R's bass is deep, punchy and has just enough body before sounding bloated. There is a ton of sub-bass to be heard here and it's articulate.
I think what really surprised me about this headphone is it's holographic sound-stage, it's depth and precision. I've owned many open headphones, yet the Z1R really knows where to place it's instruments and vocals. Sounds were coming from everywhere and it was a nice thing to experience. The details impressed me as well. I've listened to Cannibal OX hundreds of times and I was hearing things that I've never heard before. I couldn't believe it at first. The way that the Z1R handles the loud and the subtle sounds is very cohesive and eye-opening.
However, I do feel like there is some slight sibilance in the treble. This happened every now and then, but it was there. The treble also seems a bit one-note to me, and even though it can be full of energy I feel like there isn't much more to it than that. This made me realize that the Z1R is great for low-level listening, which is great. I can see why people like to relax with this headphone.
Finally, this headphone makes me bob my head and tap my feet. I think other than comfort this is what won me over. This is a definite keeper.
EDIT: I'd like to add that this headphone is VERY easy to power. I'm listening to it right now while its plugged into my iPhone 6. This is a HUGE selling point for me as I like to stay in a more relaxed position when listening to music, and because my room isn't big enough then laying on my bed is the next best thing. I'm not sure yet whether or not it sounds 'better' with a portable amp, but I will have impressions later on.