I usually just browse head-fi out of interest, but I just had to make an account to give my take on this.
I own the DT-880 250 premium which I usually pair with either a FIIO E07K, my Denon CD-deck (an apparently my Denon AVR-2312 can't drive anything, doesn't matter if it's even small earbuds or 250 ohm cans), or directly from a high grade desktop motherboard.
I know they are not amped to their full potential, but it is a night and day between just a phone's output or a laptop. And the DT-880 sound "full" when i compare them with the ATH-M50 paired with a FIIO E07K or my motherboard.
I am pretty sure, that the Beyer Dynamic range is not crap.
Of course they are not like the Beyer T1, because they are a different price-range entirely, but for their price-point they outperform alot of headphones.
And of course they do have a certain sonic signature, like most brands of headphones.
I recently bought the DT-770 32 Ohm, and they do not sound worse or cheaper than the DT-880 250 Ohm. They are more bassy, but that is just their signature.
But even if they are easier to drive, they do however improve when amped by something with a bit more power than a smartphone.
I actually enjoy my 770 and 880 so much, that I have ordered the DT-990, just to have a completely open can.
Next up is the DT-1770 i guess...