“I loved my 600's when I had them... and I had them for over a dozen years. But I almost never listen with headphones in the house anymore and when I'm out walking the open back is a detriment.”

The headline score reflects owners (Reddit, enthusiast forums), independent lab tests, and blogs with no affiliate links. YouTube and affiliate blogs are shown for perspective but kept out — hover the i for why.
“I loved my 600's when I had them... and I had them for over a dozen years. But I almost never listen with headphones in the house anymore and when I'm out walking the open back is a detriment.”
“The HD 600s can be worn easily for hours without fatigue. So much so that you can forget they are on! They remain some of the most comfortable reference headphones that I have tried.”
“the HD650 is a better headphone. It performs better technically, it gives you a bit more resolution and for sure soundstage. The HD600 has no soundstage.”
“They are a nice headphone, I like to use them for testing headphone amps that I build. While it is not a TOTL 'phone, it is representative of audiophile headphones”
“I just got a pair of HD600's last month and am very pleased with them, easily the most neutral and natural sounding headphones i've heard, with nice clarity in the treble.”
“In the end i returned the 600 after 1-2 week, because the overall sound was too harsh and lean after the 650.”
“the 600 is a bit "airier" or "brighter" than the 650, which is why I sold the 600's. But, I would be happy with the 600's, too.”
“I've been using it ever since, and haven't even touched the Beyers anymore. It's great for almost all types of music, everyone should have this one in his collection”
“I've had a couple over the years and never cared for them much”
“I found them a bit meh frankly and bland.”
“The HD600 has the most realistic timbre of any headphone I've heard (most under $600). Snares sound utterly addictive, probably my favorite aspect of the whole FR.”
“From my personal experience comparing the two headphones, the HD600 was a tad brighter and the highs were slightly less smooth.”
“As with HD650, I was yet again impressed by how good this headphone sounds. Equalization made an improvement but the headphone was very listenable without it.”
“In terms of their technical performance, in many ways the HD 600 falls short. While their midrange is incredibly clear, the lack of low end and a narrow soundstage can pose something of an issue here. The Sennheiser HD 600 has a 300 ohm nominal impedance, so you may want to consider buying a separate amp”
“The HD600 is my reference phone set. They are not perfect, but they are very good. I am not willing to pay orders of magnitude more money to "upgrade" either.”
“They beat the living daylights out of my HD448's. I don't think I can imagine a violent enough action for how badly they destroy anything I have owned.”
“In short, the HD 600 is built for listeners who want top-notch sound, but it's picky about power. A headphone amp isn't just a nice-to-have it's essential to unlock the full experience the HD 600 headphones offer.”
“I have owned them twice in the past and loved them. They seemed the most speaker like headphone I had heard. They were very neutral as well.”
“I love my hd 600. They are so balanced across the spectrum and really open up when burned it. They are also relaxed and offer great bass.”
“I too found some really significant details in music I'd listened to many time previously. Revelation of these new aspects of the music made me really understand why I paid more for these headphones. They are really special.”
“I love my HD600 and will never sell them!! They are my first step into the upper hi-fi league and I have so many fond memories of them”
“The HD600 is a really solid headphone if you're not bothered by the small soundstage but enjoy some beautiful vocals/mids.”
“My new HD600 has been burn in about 100 hours now and sounds stunning coming through my amp.”
“I do prefer the hd600 sound over the hd6xx. I agree that hd600 is brighter (than 6xx).”