Pros: Richly detailed, supremely textured, natural sound that is smooth, effortless and relaxing to listen to. A forgiving allrounder with superb comfort.
Cons: Open headphone that requires good source and amplification
I've listenend to all the top offerings from Denon, Audeze, AKG, Hifiman, Ultrasone & Sennheiser and this is my personal favourite. It is a true reference class headphone that is very natural sounding, albeit leaning ever so slightly towards a darker tone. The sound is detailed, smooth and richly textured, especially drums come alive amazingly well. It has no problem spanning all the way from the deepest bass to the highest highs with supreme control and plenty of muscles to spare.
For the money I think this is a real audiophile bargain, the HD650 exists on that plane of ultimate performance where sound quality becomes no longer a factor of quality but rather personal taste. It really doesn't get much "enjoyable" than this no matter what you pay. The HD800 has better resolution, speed and spacial presentation - but can be a bit cold, analytical and unforgiving. The LCD-3 is arguably a "better" heaphone with amazing resolution, extension and control - but in my humble opinion it can sound a little dry and laid-back compared to something like a HD650, Grado, Hifiman or D7000 which are more "fun" and energetic with a more "forward" sound.
So in short - the HD650 I think is truly great, not unbeatable in specific genres but an amazing allrounder. It should however be said that it only truly begins to show what it can do with top notch source and amplification - I wouldn't recommend driving this beauty with anything like a phone or Mp3 player due to its rather high imepedance and revealing nature.
Although "revaling" is also a relative term since they are infinitely more forgiving towards bad recodings than a HD800 or LCD-2/LCD-3. It should also be said that I do think they exhibit a slight veil (this eternal debate) but ONLY at low listening levels - so that those who find themselves always listening at very low volumes might want to also consider something along the lines of a grado reference headphone which are known for their "intimacy".
All in all the HD650 is a superb headphone that comfortably matches, or beats, competitors at more than twice its price. A superb allrounder with a fun and energetic play-style, detailed but not too unforgiving - not to be overlooked!
Edited: updated July 2012
There comes a point in the pursuit of audio excellence where you face diminishing returns based on price. The 650’s can be had for around $500 dollars. The next step up from here is the $1000 dollar price range.
Are the new Sennheiser 700s and the Audeze’s worth $500 dollars more than the Sennheiser 650’s? That’s a personal assessment we each make individually. But the step up in quality to the $1000 dollar price point is incrementally less than the jump from the $100 dollar to the $500 dollar price point. Which makes the Sennheiser 650 an important headphone to consider.
Most stuff beyond this headphone becomes marginally or incrementally better in certain areas. Are the headphones above the 650 truly better? Absolutely, no argument there.
But I’ve read a few reviews which would suggest that the sound out of the 650’s is likened to a transistor AM radio. Which indicates the reviewer is trying to make us think he knows something the rest of us simply can’t comprehend, which is retarded.
If you’re reading this, you have a passion for headphones and music. As such, I enjoy reading what you think about stuff you’ve tried, and stuff you own, even if you don’t agree with me. That’s part of the fun of this hobby. The many different reviews of the Sennheiser 800s are one of my favorite parts of this website. How so many different pairs of ears have a different listening experience with the same equipment is fascinating. I can't wait to add my own verse some day.
I suspect I will be diving deeper into the $1000 dollar category in the future, and playing with different amp and can combinations for the fun of it. And the sound does get better (and worse!) with different combinations, no question.
But to suggest you won’t have a good experience by plugging a pair of 650’s directly out of your iPod or MacBook is a stupid comment by stupid people. It’s elitist BS that adds little to the discussion.
Hope that wasn't too harsh! :)
I'm on board with everything you say, with the exception of this comment. After all, we are talking about a 300 ohm headphone with a specific impedance of 475 ohms in the 40 - 70 Hz range. iPods are intended for earbuds with 32 ohms impedance. How is it elitist to point out the two are really mismatched?