I had a nice, private session with the YH-5000SE earlier today. It's easily among the best built and most comfortable headphones I've ever used, although the actual design can come off steampunk-like (appeals to me). Excuse the purple lighting, Yamaha decided this ambient lighting enhanced the experience lol:
As you can see, Yamaha has decided to pair all demo units with the RME ADI-2. The local reps weren't sure why except that it was how everything was shipped with clear instructions to match them. They also mentioned the goal was to have a neutral sound without the most extension on either side to make for a non-fatiguing and natural presentation (their words, not mine). In practice, I did note the drop off in the sub-bass which makes this a more mid-bass focused set followed by some of the best mids reproduction. Indeed, I kept thinking about how this is a better HD 650 in that regard, although I would have preferred some more ear gain and upper mids presence. String instruments and piano keys do get their fair dues at the expense of vocals, especially female vocals. The upper treble also dips down but doesn't feel as dark to where orchestral music should be plenty fine here. Overall I'd like to get a set in for review and to see what this can do paired with other sources as I was getting close to maxing out the RME in the default settings they had, I couldn't change anything on it. They also said the UK is getting all of 30 units this year and that right now the team in Japan can't make sets fast enough to fulfill the pre-orders.