Let me preface this review with, I am not an audio snob. I own 2 pairs of headphones and 1 pair of IEMs. I am listening on my PC using an SU-8 dac and an SP200 headphone amp. I assume what your listening on is probably as important as the cans.
After seeing the reviews I was pretty excited to grab these headphones. I also have a pair of AKG K702 that I picked up for about the same price. In my opinion, when comparing the two its not even close. I listen to a wide range of music.
K702 - lighter and more comfortable
auto adjusts to head size
replaceable mini xlr cable
softer sound with a wide stage
lower sound at the same volume
better sound for most music that I listen to
DT990 - clamps pretty tight on my head
manual adjustment thats stiff
non replaceable cable
muddy bass heavy sound
louder more in your face at same volume
I was surprised that the AKG were softer and less loud at the same volume. The AKG have lower impedance so I assumed that they would be louder. My main gripe about the DT990 is the muddiness of the sound. There is definitely more oomph to music at the cost of clarity. If I could find headphones somewhere in between these sound wise with AKG's build quality, they would be near perfect for me.
You might like the sound signature of the Hifiman He-560 (which I own) or the HE-5xx (which I have on the way). They have great separation and precision, and a focus on the mid range (vocals, guitar...etc.) compared to the DT990 which is more treble focused. I owned 5 different headphones before circling back to the Hifimans as the best headphones for my taste.
Any BD phones with the "Pro" designation fit tightly by design, so they don't fly off during a rowdy studio session. It's a feature, not a bug.
The hyped bass is also on purpose. That's why I prefer the DT880 (supremely comfy) and DT1990 Pro; they're flatter across the spectrum (for BDs, anyway). And the 1990s dig down to 10 Hz -- accurate and glorious at the same time and worth every dollar!
You're correct about the comfort of the 702s. They're excellent in many other ways, too...as long as you don't need to reproduce any content under 50 Hz. What gives, AKG??
Btw DT-990 has full metal headband, if it clamps too hard, you can just bend it slightly to ease the clamping force. That's what I did on my DT-770 Pro. Definitely not going to break it unless you're about do like 90 degree bend on it.
What comes for comfort, my DT-770 has stayed the same for 5 years but my AKG K712 Pro's headband's elastic died in two years and the replacement costs €80 and there are no replacement parts sold in Europe. So go figure, if the 990 doesn't have the sound signature you like, I'd still look for other Beyer options for comfort or better sound. Just the longevity of the product is what I like. AKG has shit customer service now that it's owned my Samsung.