This is going to be kind a hodgepodge of a comparison. I have been in an out of the Hospital for the last 2 months due to my health. Still not quite all here. So forgive me if I babble incoherently about something that doesn't make sense. I will also try to upload the Fequency Response charts of my headphones once I get a chance. I personally don't care about them but I know they are important to some.
Rognir: ECL-03 pads. Thror: ECL-02 pads. Final: Stock pads. Listened to all on my R8MK2 connected to my Master-9 which is then connected to a 3 way switcher for rapid headphone swapping.
The Rognir, Thror, and d8k Pro are pretty similar in overall performance. which is to be expected once you get into the Flagship market of headphones. The main differences will more-or-less come down to tuning.
I will do my best to explain the difference between them to the best of my ability. Though, I'm not great at this once the price of headphones gets this high. I figured, since bass seems to be the main thing people want to know about, and it is easy enough to compare, I would do a quick direct comparison between the Rognir, Thror, and D8000 Pro
Bass- Rognir>D8000 Pro>Thror
Rognir:
This is still the king of bass to me. It has more quantity than the other 2 with out it being over barring. It has incredible speed and control with out taking any of the life out of it. It reaches deep into the lows with excellent sub rumble.
D8000 Pro:
Reaches just as deep as the Rognir but lacks the quantity and presence of the Rognir. It has a great sub bass rumble but seems lacking compared to the Rognir. Bass is just as fast and controlled as the Rognir.
Thror:
Least amount of bass of the 3. It's bass so tight and controlled with such a hard and tight snap that it tends to lose a little of its life. Doesn't reach quite as far in to the sub bas as the other 2. Lacking in sub Bass rumble compared to the other 2.
Now on to the rambling.
Basically all I learned from doing this is that all 3 headphones are incredible. They all have there strengths and weaknesses. Though due to how velvety the D8000 Pro is the Thror and Rognir end up sounding hollow when you swap to them after listening to the Final.
The D8k Pro is a Velvety smooth listening experience that is incredibly hard to beat when it comes to kicking back, putting your feet up and just listing for pure enjoyment. Though I did find that micro details and and very quite instruments tend to get pushed to the back can can be lost in the sea of velvet that is these headphones. Of the 3 the sound stage is the smallest on these but only by a very small amount. They are also the most comfortable and least fatiguing of the 3. You can, and I have, listen to them all day with out any problem.
Example of quieter instruments being pushed back on the Final. In the beginning of the song, City in Florida by DeadMau5, there is a pretty quite "squishy" noise that plays along with the beat. On the Final it is about half as loud and much further pushed out of focuses compared to the other 2. It is still there just much less noticeable when compared to the Rognir and especially when compared to the Thror.
The Rognir is all about speed and attack with an in your face sound signature that is super engaging and energetic. They have a fantastic airy quality to them that give a boost to the overall sound stage that surpasses the Final and is on par with the Thror. Which is incredible for a closed back headphone. They are perfect for high energy songs and listening. They have pretty similar detail level to the Final, maybe, ever so slightly, a little bit less. They are the best when it comes to bass and are going to be hard to de-throne. Due to how energetic they are. They can be pretty fautiuging for long listening sessions. They demand to be listened to at high volume and you will find it hard to disagree with them. So I can really only listen for 2-3 hours at a time before my ears need a break. They are also probably the least comfortable of the 3. Not say they are bad just not a big fan of self adjusting headphone since I can't set the fit to be perfect for me.
The Thror is the most neutral of the 3. They kinda fall between the Final and Rognir as far as signature goes. Not nearly as lush as the Final and no where near as violent and in you face as the Rognir. When it comes to micro details the Thror is so accurate it is frighting. While listening to Spokey Dokey by the Seatbelts I was able to hear the lips of the harmonica player make the slightes "smack" has they would come off the harmonica when he would go to breath a detail that doesn't even exist when listeing to the song on the either the Rognir or the Final. I thought there was something wrong with the Thror when first listening to the song since the sound didn't exist in the other 2 headphones. Of the 3 headphones the Thror is the best when it comes to instrument separation, presence, micro details. It as has the largest sound stage just beating out the Rognir. They have the least bass of the 3 and have almost on sub bass rumble. So you are trading Sub bass and bass quantity for absolutely insane levels of detail.
In summary. If you want maximum detail get the Thror. If you want the most enjoyable all day listening with excellent bass get the Final. If you want energy, bass, and excitment get the Rognir.
P.S. Was to lazy to pad swap on the comparisons. So just used what I considered to be the "best" pads on the headphones.