Sennheiser HD 600 vs. HD 550: Which is better?

When people talk about “sensible” headphone purchases, the conversation inevitably circles back to Sennheiser’s mid-fi staples. The HD600 and HD550 sit right in that sweet spot of price, performance, and... sanity for lack of a better term, such that both have become staples of their price range whenever anyone asks for purchase advice for "neutral" headphones.

The HD600, probably more than any other headphone on the planet, has the reputation as the neutral, flat, plain-water reference headphone, and… yeah, I’ve probably contributed to that narrative myself.

But the truth is that the 600 isn’t boring at all, nor is it completely free of coloration or editorialization. There’s a little extra sweetness, and importantly, a little extra warmth &  low-mid richness. These things convalesce into a distinct character—one shared with the 650/6XX, though its a little more clear and open sounding—that makes these headphones not only "natural" but interesting and enjoyable.

The HD550 on the other hand is the one that actually leans even harder into the “reference” approach. Same excellent midrange, for sure, but with a more even bass shelf and better sub-bass extension. It lacks the upper-bass/lower-mid push of the 6 series which makes it sound even more clear and focused, and while this means its potentially a bit less forgiving, If you want a genuinely "reference" tuning, I actually think the HD 550 is the better choice.

Build and comfort certainly diverge meaningfully as well, where the HD600’s 6-series chassis still feels sturdier and more premium, with the iconic 6 series silhouette and a potentially vise-like clamp (that can be tamed by bending the metal arms). The 550’s 5-series frame is lighter and looser in clamp, but the pads run a bit shallow—your ears may brush the baffle unless you shift the cup forward slightly—and the headband is probably not going to be as comfortable for smaller heads since there's no cut-out in the middle of the headpad. Ultimately its just gonna come down to your own head shape/size; I'm a big head boy so I appreciate the looser clamp of the 550, but I also prefer the HD 600's ear chamber comfort and headband padding.

Sonically, I think it's underestimated how much these things trade blows. People treat the HD 550 as a bit of an obvious downgrade from HD 600, but I really don't think it's that simple.

The HD600 gives you that classically lush low-mid body, and a treble profile with a little extra emphasis—what I'll call “frosting”—above 10kHz (yes, the 600 absolutely has upper treble, do not listen to people who say otherwise). 

The 550 pushes cleaner through the mids thanks to its flatter bass profile, and for that reason I actually found it to work fantastically well for jazz and acoustic recordings. However, for more aggressive genres like rock and metal, where a little extra meat on the bones is nice to balance out potentially harsh elements or recordings, I tend to favor the 600’s warmth and euphony.

Both are timbrally superb, especially on vocals where really, I can't discern a clear preference for one over the other. I cannot stress this enough; both of these headphones get the most important part of the tuning exceptionally right.

Now, they have meaningful differences in the treble on my head; the HD 600 is a little more filled-in in the mid-treble, which helps the spritziness above 10 kHz feel a little more balanced and even-keeled, but the HD 550 has a slightly more relaxed ear gain peak.

HD 550 also has a trick up its sleeve the HD 600 doesn't: depending on how you wear it, you can considerably reduce the upper treble of the HD 550 such that the slight grain and glare it has up top gets much more relaxed.

So while I think people who hear both of these may end up having a clear preference for one or the other... for me, it's really not that simple. Both make an incredibly strong case for themselves, and I really can't say either is a clear winner over the other. The choice comes down to music choice, preferred ergonomic/design profile, and of course, sonic flavor. With the HD 550 you get a headphone that's arguably more neutral and definitely more extended, and with the HD 600 you get a headphone that is, yes, mostly neutral, but also slightly enriched and sweetened in a way that's really quite addictive when it works.

For that reason, I can only come away recommending people try both and picking their favorite for themselves.