Man, these are getting better and better. Indeed the bass fills in(It was too little for me on the day before yesterday, but now it's enough), the midrange also become denser, warmer. I was ready to sell them initially, because it was too lean in the midrange, and there was a fairly big peak in the upper mids.
Concise comparison between DT880 250 OHM and Shure SRH1840:
Build quality is slightly better than the DT880's, it feels solid in the hand. It is almost all metal, except for the headband which is made of plastic with some synhtetic leather(pleather) coating. I'm very surprised that it is much smaller sized headphone than the DT880. The cable itself is is very high quality, it's coating is made of some high quality rubber.
The fit is great for me, even as I have bigger ears than the avarage size.
Comfort wise these are almost on par with the DT880s, the DT880s being a bit more "breezy" for the ears, as they have larger earcups.
Headband adjustment is easier with the SRH1840s, as their headband adjusts smoother than the DT880's.
It leaks quite a bit of sound, but it's not worse than with the DT880s. Personally I don't care about sound leakage, that's why I always bought open design headphones.
So far the bass is much tighter, more textured(with a growling timbre), and extends even deeper than my old DT880's bass. But it is fuller as well.
The midrange is more pronounced, much warmer and fuller(big difference), with more resolution and air.
The highs are much smoother(big difference), less grainy, and more extended than the DT880's treble, and also much lower in quantity, causing a non-fatiguing, flowing sound.
Soundstage wise these are great. It is fairly bigger than the DT880's, but their imaging is simply more precise. Every instrument is well seperated, you can identify each instrument without making efforts.
I can hear more details, than I heard with the DT880s.
Overall I think it is well wort the difference in the price, and I can recommend this headphone wholeheartedly for everybody, who is seeking for a good all-arounder headphnoed with an open, spacious sound.
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The only problem is that now I have 10 hours on it, but it still has got a slight peak in the upper midrange, Which I'm not fond of. I hope it will disappear after burn-in.