This review is based solely on my experience.
Like a culinary art, where a chef puts together the right ingredients, one must put together the right equipment to get the perfect sound that's right for you. But then again, some will like the recipe others will not, just like the Sennheiser HD650, some hate it and others love it. Put the right equipments together and it could be your end game. There is also the psychological mindset that getting an expensive headphone will naturally sound better or sound superior to lesser costing ones. But I believe it is subjective of the matter and is not always the case, we all have different taste in sound signatures and music. I've gone from world class planar magnetic headphones down to dynamic reference class like the Sennheiser HD650. And to my ears the HD650 sounded the best, because I have come to understand how to remedy what is lacking and overpowering in a headphones sound signature I found that the HD650 can reveal not only what the artist intended for you to hear through your lossless music files but also reveal how a DAC sounds, an AMP sounds, a CABLE sounds and even a POWER SUPPLY. It is that sensitive! It is very flexible! In between 32-600 ohms, at 300 ohms it can produce sound signatures both ways depending on the equipment. You can tighten the bass, extend the highs, bring forth the mids and so on or vise versa by experimenting on different gears. It is truly an all rounder, it has the potential of competing with its higher siblings if you have the right combination of the HD650's secret ingredients. There is not limit to the HD650's potential, there is only limit in your imaginations.