I personally wouldn't trust z review on everything especially when he bases conclusions on high end headphones without even trying to match it. That's just not how it works when you go above a certain level and most of them in the price range have fantastic detail and extension which will certainly make some recordings sound too bright, lean, sibilant etc. Hence the reason for people rolling amps, tubes, op-amps and what not to match their own tonality preference. It is really interesting to hear the differences in tonality by swapping certain parts.
Had the HD650 w/ NFB-11, sounded very special. I felt like I was experiencing the exact same things as other people's impressions, so that was really interesting. A lot of people called HD650 as being veiled, but I think the new revision and the NFB-11 match made it just the right amount of brightness for me. The laid back signature was really something. I saw tremendous amount of people keeping their HD650 and spending more on matching. IMO was just not worth it as there are a lot of headphones to be had for better technicality in terms of resolution, extension, and openness. I think it's one of those headphones that a lot of people go by during the audiophile journey.