I am really surprised to see so many positive reviews on the DT 770.  To my ears, the sound this headphone renders is muffled.  To my ears they sound as though someone has placed a heavy cloth over the microphones before recording.  That muffled sound distracts from the details heard from the music.  The frequency range is not well balanced on these headphones, in my opinion.  The mid frequency range is too loud compared to the rest.  There isn't enough for my tastes from the high and low frequencies.   This is definitely not a headphone I would use for any type of audio recording analysis.  Their sound is dull and boring, in my opinion. 

I have owned the Ultrasone Pro 750 for approximately 6 years and to say that I am familiar with the sound of this particular headphone would be an immense understatement.
As a highly experienced listener to the Pro 750 I can readily assure all of the people who have written negative reviews about this headphone that there is something wrong with either the way you are using the Pro 750 (such as improper placement on the ears or faulty or inappropriate amplification) and not with the Pro 750 itself.  The only exception to this would be a case, a rare case, involving your having had a defective pair of the Pro 750 or possibly another type of rare case involving the particular listener having a "incompatible" pair of ears.
There will probably be not only those who claim to disagree with me but who also disagree vehemently.  I used to post on this website frequently approximately 2 years ago and I read many reviews of various headphones.  What these reviews taught me is that headphone preference is highly individualistic.  I remember one particular Head-Fi member who asked me to make comparisons of the Pro 750 to other headphones.  I answered that member rather vaguely simply because I did not want to insult those who preferred other headphones or argue with those who claimed that the Pro 750 has some type of offensive sound. 
Once again, I can attest from personal experience that merely by changing the position of the headphones on one's head thereby affecting the positioning of the cups on the ears dramatically changes a negative opinion of the sound of the Pro 750 to a very positive one relating to the aforementioned conditions inclusive of appropriate amplification. There is most definitely a proper way to wear the Pro 750 and that positioning on the head and ears could well be different from the position to which you are accustomed.
In my opinion, appropriate amplification for the Pro 750 is the most neutral "flat" response possible.  The Pro 750 will render a very realistic sound under the right conditions.  If your preference is to not hear what the recording producer and engineer intended you to hear, either listen to the Pro 750 with an amp that alters the sound or use a different headphone that either has a completely "flat" frequency response or one that alters the sound differently than the Pro 750 does. 
Whoa! What did you just read?!  Did Peter Pinna actually write that the Pro 750 alters the sound?  Yes, I did but the Pro 750 alters the sound in such a way as to cause what you hear through them to sound like "flat response" audio coming from recording studio monitor speakers in a controlled ("dead") room environment.   I used to have the mistaken belief that the Pro 750 were "flat" response headphones.  The reason I held this belief was because there was very minimal (hard to detect) difference between the sound coming from studio monitors in a controlled environment compared to the sound given by the Pro 750.   It was pointed out and exemplified to me that the sound of audio as one hears through the Pro 750 has to be altered to cause that sound to come across as what our ears hear as a "flat" response from an acoustically controlled room speaker.  Actual "flat" response from a headphone does not "sound" like a "flat" response as the sound would come from a speaker in a controlled environment. 
If you want to hear what an actual "flat" response headphone would sound like, go to a store that sells very small speakers and buy two of them.  Only buy speakers and not speakers in a housing. Put the speakers simultaneously by each ear and listen to some music played directly from the built-in amplifier of a sound source such as a phonograph.  It sounds dull and annoyingly "colorless" doesn't it?  Well, that's what a "flat" response headphone would sound like and that is the reason that "flat" response headphones are not sold generally to those who want to use them for music listening.   “Flat” response headphones are used in industries for only voice communication such as the Aviation Industry.
If you are able, take those two aforementioned speakers with you to a recording studio and have one of the engineers play some music for you. I suggest a classical piece played by a Symphony Orchestra. You might try Brahms “Double” Concerto for Violin and Cello in A Minor because there is a fairly wide spectrum of high and low frequencies in this piece of music. First have them play the music through their monitor speakers in their control room. The control / listening rooms in most professional recording studios are acoustically balanced so that there is no or extremely little resonance (an acoustically “dead” room) detectable.
Listen to their monitor speakers for awhile so that you become accustomed to the sound. Then have them turn off the monitor speakers and play the music through the two little speakers you brought with you. Hold the speakers next to your ears as if they are headphones. It sounds awful doesn't it? Once again, you would be listening to small speakers that are rendering a “flat” response. One reason they sound awful is because they are right next to your ear. Part of the reason the “flat” response monitor speakers sound so much better is because they are a distance from your ears allowing the sound that you perceive to be affected by and radiated off the pinna of your ears.
Next, ask the Sound Engineer to play the music through the monitor speakers again. Once again, become accustomed to the sound they produce. Then, put on a pair of well “burned in” Ultrasone Pro 750 headphones and have the engineer run the sound through them after turning off the monitor speakers. You will be amazed at how extremely similar your perception of the sound from Pro 750 is compared to the sound you heard from the monitor speakers. The audio coming from the Pro 750 sounds very similar to the audio coming from “flat” response monitor speakers in an acoustically controlled (“dead”) room.
The Pro 750 is an extremely revealing headphone. When properly worn and with the correct neutral amplification, through them you will hear musical detail you've probably never heard before. The sound textures are rich and vibrant. The high, middle and low frequency range is well balanced and very “alive” sounding. The realistic sounding music surrounds and captivates you as it plays beautifully through the Pro 750. Yes, let there be no misunderstanding, I am emphatically stating that the S-Logic effect is definitely heard from the Pro 750 and some recordings reveal this effect more than others.
If you are considering the buying of a headphone, I strongly suggest that you hear whatever headphone you are considering before buying it. Make a decision based on how your ears and brain perceive sound.
Thank you for taking the time to read this.