The Trailii's are somewhere between Amsterdam and God knows what customs ... I don't think they're due to arrive till well into next week. I'm hopeful they will be somewhere between the Utopia and Empy's but can be driven out of anything ... i.e. sound magnificent out of my SP2000 without having to buy an amp.
The Empyrean's and Utopia are tonally quite different. The Empy's really need power to open up and show their best. The SP2000/Hugo2 isn't enough ... plug them into the same type of amp you'd drive the LCD-4 out of. They deserve it. They have a silky smooth, musical tonality and timbre to them that is best listened to rather than described. Underpowered, they sound congested and dull with inadequate dynamic drive. They're the headphone I would use if I want to lie on a recliner and just chilax. The separation isn't quite Utopia but apart from Susvara, I'm not sure what is.
The Utopia are my 'plug into anything' option. The other was the HE1kse but nobody had one for me to audition. They've heavy, clam somewhat tight and not as comfortable. But at least they won't fall off if I tilt my head. I'm finding them slightly bright which may/may not improve with burn-in. The detail and separation and very enjoyable. A cooler (but slightly warm) side of neutral as opposed to the Empy's warm neutral. And enough of a bass kick when required, which the HD800S sorely lacks.
These Utopia's are literally 3 hours out of a box. So these are fresh impressions.
The Susvara are undeniably better than Utopia and Empyrean but are a bitch to drive. Like seriously need to spend double the headphone cost on an amp to get the most out of them. The last time I auditioned the Susvara, the chain was ROON -> Mind2 -> Moon 430HAD.