Just relistened to the Abyss 1266 yesterday vs the 4z and Utopia. While they are better in many regards they are not imo the be all and end all in headphones. I would take two good headphones over them any day. I would buy the Empyrean and Utopia or Empyrean and Arya over the Abyss alone.
That goes to show how experiences can be so different. I adjusted the 1266 to many angles and still found them very clampy on my big head. Even more so than the 4z......and Audeze’s are know to have high clamp pressure. I actually find my HEK SE’s to disappear more than the Abyss. The Abyss do have a deeper soundstage though. I would take the Susvara all day over the Abyss.
I've listened to the LCD 4, 4z etc. I did side by side auditions of the LCD 4 vs empyrean before purchase. Imo the empyrean was ahead of the 4z in all aspects, detail retrieval bass quality/quantity, and treble with more lifelike mids. To me the empyrean has a wider soundstage and a much more comfortable fit than any audeze headphone (and a more comfortable fit than most any headphones). The 4z may be a little more of a balanced/neutural sound signature with the empyreans having a bit of a bass hump, but not too much to be a negative. The really big difference to me is that the 4z and even the lcd4 to me are not near as enjoyable to listen to music with. The empyrean sounds so much more life like and realistic, instruments sound as they should. Again my own impressions but I suggest listening to them both as both have a good following for their own reasons.
They are both very good headphones, so I recommend to audition them before you decide.
The 4z had better resolution, especially in the base and treble, but the Empyrean was somewhat close. 
I'm not sure if you used leather pad or Alcantra one. But Imaging is much better and precise with leather padI compared both over multiple visits to a demoroom
The Empy had a fair bit wider soundstage, while being a little bit worse in imaging. The 4z has more of a giant globe type of sound that had a nice verticallity to it.
Now comfort and build was miles better on the empyrean.
Really up to preference.. i was awestruck by the resolution om the audeze, so i went with that one..
I tried and compared both, empyrean with Alcantara pads and LCD4Z, both with their stock cable.
I had the 4z once and stuck with the 4 for the same reason. I thought I was imagining the "slightly veiled sound", but seems like I'm not the only person who hears that from the 4z. It's still a great headphone, but if you have the amp to run the 4 and don't mind the weight, for the same price, might as well go for the better sounding (and looking) LCD-4.
Never heard the Empyrean though, so just wanted to chime in about the LCD-4z
its just my opinion so take it for what it is, but the LCD-4z seems to be over priced for what you get sound wise... there is a huge difference in sound between it and the LCD-4.
