Mini review
They compare in sound to....
ATH-ESW9 and Ultrasone Edition 9 are what I have to compare them with today.
ESW9 is warmer less detailed and less precise. ESW9 was ~290 and the 780 was ~200 delivered. ESW9 are more comfortable and lighter. The 780s have the Ultrasone clamp out of the box. It will loosen up after a week or so. To me these two have almost opposite sound profiles with the 780 being more aggressive. Image width is bigger on the 780s than the ESW9s. The 780 has very good sound image in my opinion.
Edition 9 must have been a test bed for Ultrasone since they appear to have moved it's sound into the 780 so much so that I had just ordered myself a second UE9 which was on backorder only to cancel it after hearing these. I am having a hard time differing the sound from these two with the 780 right out of the box. I wonder how the newer Pro 750s will compare given that they will have the upgraded pads and mu board material. The Pro 750 have the same drivers as the UE9s while the 780s have a different driver but I would have not known it if I had not read it. The UE9 has S-Logic while the 780 have S-Logic Plus for what this is worth to you.