[galneon]

Edit: I bet this happens a lot... I talked myself into ordering the DT 1990 Pros despite the 3-pin XLR connection. I can change it to 4-pin no problem.

I recently got a Fiio M11. My HD598s are fine for what I got them for years ago (transcribing music) and I will likely keep them to that end, but they're boring to listen to. Accurate enough, but not much fun. I appreciate accuracy, but need a balance between it and enjoyability when listening for pleasure, and I don't get much enjoyment from the 598s.

I first looked to the HD660Ss. They seem like a safe bet and have a 4.4 mm connection, and it seems commonly accepted that they're a much more entertaining experience than the 598s (which are known to be pretty dull--the revisions seem a little better in this regard) while still being accurate.

I had a friend with similar taste who moved from $400-600 Senns to 400-600 Beyers years ago and never looked back. Someone in the HD660S thread just suggested I look into DT 1990 Pros, and while I have no doubt I'd enjoy them, there's no balanced option and I will obsess over the fact that the 2.5 and 4.4 mm outputs on my M11 will likely never have their seal broken, for I'm hoping my quest is not a perennial one. To that end, the Z7 MK2 with 4.4 mm was suggested, but I'm partial to open-back and have concerns about too much bass. I'm also often on-call and require some awareness of my surroundings...

I've read the DT 1990 Pros don't even really benefit from a balanced connection given their specs, but you know how it is... :/ I'm a pro with a solder iron and the 3-to-4-pin XLR mod looks braindead simple, so that is an option.

Budget is flexible, but I don't want to ruin my stereo speakers, which I am satisfied with, by spending significantly more than $500 and blowing them out of the water. Then I'd have to replace my stereo speakers, and the cycle would never end...

(Unfortunately, I can't audition headphones anywhere near where I live...)

 

[Mhog55]

Not being a huge fan of the beyerdynamic house sound, I'd personally roll with the 660s unless you want to jump to planars.

 

[galneon]

Not being a huge fan of the beyerdynamic house sound, I'd personally roll with the 660s unless you want to jump to planars.

I'm afraid of planars--I don't want to spoil myself. The 660S is definitely my backup purchase if I can't get into the 1990s.

 

[pietcux]

The DT1990 PRO are a modern deviation from the typical Beyer house sound. The young engineering guys changed the sound by reducing the spikes in the frequency range. The Amiron Home is quite similar, but has less clamping force.So both the DT1770 and DT1990 sound very balanced compared to the DT1770/880/990. I had both in parallel for quite some time. My policy is to let go some headphones, once the headphone closet overflows. It was a tough decision, but being terminated balanced firsthand I kept the HD660S.
I recently aquired a used Beyer T5p 2nd Edition. Boy what a gorgeous sounding and spacious closed headphone... Same as with the DT1990/1770 very balanced, but still more dynamic and a quantum more bass, which is the fun part for me. And those are prepared for being balanced already. Plus at 32Ohm they are very easy to drive. Buy them used plus new pads. Got mine including the new pads for 490€.
Btw, to modify the DT1990 to being balanced you could also buy a second left earcup. Then you could use a lot more cable already available.