Advice Needed deciding new Phones

Given your tastes and other equipment I’d highly recommend the Hifiman Arya v3 Stealths. I have them and they retail for $1700 but there’s a nice used pair on USAM for $950 you might be able to negotiate on since he’s the second owner. They are very transparent and open sounding and give me a lot of the satisfaction of the large 3D soundstage and detail of my big rig — lots of outside the head imaging in other words — and they’re relatively not that hard to drive so you might be fine with your nice DAC in that regard, but do check just in case.  They are open-backed so sound will leak out and other people will hear, if that’s a concern. Read the reviews (I totally agree with the review on soundnews.net BTW), but I wouldn’t wait on these as they’ll surely disappear fast. I can also help on cable recommendations if desired. Hope this helps, and best of luck.

https://www.head-fi.org/classifieds/hifiman-arya-se-v3-fs.29128/

Try a model from Grado......I find them very musical.....get them from Amazon, and return them if you don't like them.

I’ve got some Grado from the prestige line, and they can be good with the right gear. Perhaps their higher end stuff would be worth a listen. The OP has a fondness for the Sony MDR V6, and I have a pair of the Sony 7605, which is apparently quite close in sound.

But what sounds even better than the Sony’s is the Beyerdynamic DT 770. Detail with very open sound, but not harsh like the Sonys. Made in Germany and not terribly expensive, it’s been in production for around 20 years. In fact, they have recently come out with a new model in the range, and many long time DT770 owners like the improvements.

The DT 770 comes in 3 flavors. 32ohm, 5’ cord. 80 ohm, 10’ cord. 250 ohm, coiled cord. All are hard wired, around $229 each model. All do 5 Hz - 35 kHz. If you prefer open back, the DT 990 is the model. The 80 and 250 ohm versions require a headphone amp.

The DT700 is the new model with different speaker coils. 48 ohm only, detachable cord. Comes with 2 cables - 5.5’ and 9’. $350.

The $700 budget level would need a pretty good headphone amp to take advantage of the SQ available. My Schiit Jotunheim at $400 would probably not be enough for a $700 pair of cans. But the DT 770 are so good at presenting a soundstage, they are the equal of my Hifiman Sundara. The OP might not need to spend more…

I’m going to have to amend my above comments, as the T&A unit that the OP will be using costs multiple thousands of dollars.  It can probably drive anything…

In that case, the $750 budget would be quite reasonable.  I still like Beyerdynamic for the OP’s set up as they have an open detailed house sound that is superior to those old Sonys.  Just move up the line to the T1 model.  It’s open back, which is generally superior to closed back.  It might disturb others in the room at higher volumes though. 
 

Slightly over the budget, but worth it.

My Dac 200 offers no specs on the headphone aspect other that the jack is a 4.4 mm Balanced Pentacon.   Thanks for all of the great suggestions.  I re foamed the Sony’s so I will have a point of comparison to the others.   

Given your tastes and other equipment I’d highly recommend the Hifiman Arya v3 Stealths. I have them and they retail for $1700 but there’s a nice used pair on USAM for $950 you might be able to negotiate on since he’s the second owner. They are very transparent and open sounding and give me a lot of the satisfaction of the large 3D soundstage and detail of my big rig — lots of outside the head imaging in other words — and they’re relatively not that hard to drive so you might be fine with your nice DAC in that regard, but do check just in case.  They are open-backed so sound will leak out and other people will hear, if that’s a concern. Read the reviews (I totally agree with the review on soundnews.net BTW), but I wouldn’t wait on these as they’ll surely disappear fast. I can also help on cable recommendations if desired. Hope this helps, and best of luck.
Regard:

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Try some of the Meze 'phones, Grado 'phones and HiFi Man 'phones.