Bests & Worsts Reviews from Amazon

(If you're wondering how these compare to the Sennheiser HD 600 Open Back Professional Headphone, please see the bonus section that follows this review.) These are, bar none, the most wonderful headphones I've ever heard. For perspective, I have or have had: Audio-Technica ATH-M50 (of course) and M40x, Fostex T50RP MK3, Oppo PM-3, Philips Fidelio M1MKII and L2, and both the Sennheiser HD598SE and HD600. None of these but the HD600 come close. If you're considering the HD598 as a lower-priced alternative, it's a great headphone in its own right (especially if you don't want to go down the rabbit hole of choosing a suitable amp), but there isn't as much family resemblance in the sound as you might think. Still, it was through buying the 598 that I decided to take the plunge on the 650—Sennheiser's 5xx series is clearly a gateway drug to the 6xx series, which fortunately is so good there's little reason to step up to the 700 and 800 besides bragging rights. There's a lot of warped machismo in the world of audiophilia, and to the greatest extent possible I'd like to avoid that in this review. Simply put, the 650 is about the best all-around headphone you can buy for its current Amazon price of $315.99. If you already have an amp and/or a dedicated listening setup and you've never heard these, you owe it to yourself to try them. Worst-case scenario, you don't like them and you're out $6-7 for a return label. Best-case scenario, you find out just how good (and yes, also how bad) recorded music can sound. These are very much the BMW 5-series of the headphone world: there are bigger, faster, and more expensive options, but these remain the perennial gold standard. Maybe they're not your style, but there's no denying their refinement and artistry. I think they sound absolutely perfect. Some complain they're too "laid back," even "veiled." I suspect those people just don't hear very well, because if you have sensitive hearing, "exciting" headphones are a euphemism for "death by treble." I have dog-like hearing, and most of the time it's more curse than blessing. Even with the 650, the treble can be brain-piercing with the wrong amp. As for amp recommendations, this is a contentious and fiercely debated topic. As a general rule, you should spend the most on the final device in your playback chain (speakers/headphones), and progressively less on the "upstream" components: amp, DAC, media player. Given a budget of no more than $300 for an amp, you could buy the excellent Aune B1 Class A Portable Phone/Headphone Amplifier and still have enough left over to pay for a year of streaming music. Of course, if you want to pair the 650 with "endgame" gear, by all means do! The 650 has a reputation for "scalability," meaning its sound will (allegedly) continue to improve with better amps, DACs, recordings, etc. My own gear is fairly modest, so I can't speak to how this sounds plugged into a $5,000 amp or rewired with $700 cables. I will say that it REALLY comes to life with a tube amp (I have a Darkvoice 336SE), but I completely understand if that's a can of worms you'd rather not open. All I know is that the 650 sounds good enough to be the end of the headphone rainbow for me. The audio hobby is usually a desperate, futile struggle against diminishing returns, and as far as I'm concerned, the 650 IS that threshold in the headphone world. In other words, you can spend ten times more, but it won't sound ten times better. Given that, you might be wondering whether you even need an amp with these. "Need" is a strong word, and in the context of expensive headphones it's pretty hard to maintain a sense of perspective. I've done the unthinkable and plugged these directly into my iPhone's headphone jack, and you know what? They STILL sound phenomenal, but only for easy music. What's easy music? Pop, rock, basically anything recorded to be uniformly loud. Without an amp, the 650 can fall apart on classical and jazz recordings with a wide range between loud and quiet sections—there simply isn't enough power on tap to move the diaphragm as nimbly as this sort of music demands. If you never listen to instrumental music, you might be able to get away with not using an amp, but I can't recommend it. Buying such marvelous headphones and not amping them properly would be like buying a beautiful painting and not framing it. You can do it, but for a little more money you might as well get the full effect. Let me end with some totally subjective words that describe the sound of the 650: rich, natural, musical, effortless, clean. Now some words that could just as well be applied to a fine wine (the combination of status anxiety, groupthink, and reckless cognitive bias unites both hobbies): broad-shouldered, velvety, well-mannered, savory, harmonious. In either case, a smooth finish. :) Bonus section: HD650 vs HD600 Obviously if you've read this far, you're deep enough into the audio hobby to have realized an important psychological truth about yourself: you can't leave well enough alone. Neither can I. That's why, even after falling head over heels in love with the sound of the HD650, I ordered the HD600. I just had to know. The verdict? It's almost too close to call, but for my preferences the 650 is the better headphone. The two have been compared to death online, but if you have the capacity to think for yourself, audio review sites and forums are usually an unsavory if fascinating combination of shilling, self-justification, and "follow the leader" parroting of received opinions. Many self-proclaimed "audiophiles" have strong opinions about equipment they've never actually heard, which I can't accept. Given that, I decided the only way to compare the two headphones honestly was to listen to both myself for hours, going back and forth on a wide variety of recordings. The difference between a good recording and a bad recording dwarfs the difference between lossy and lossless, and the HD600 (more so than the HD650) may end up changing your taste in music because it makes good recordings sound SO GOOD and bad recordings sound SO BAD. In other words, it reveals the "truth" of the recording, and sometimes the truth hurts—it's really hard to enjoy The Killers now. The fact is that the 600 and 650 are ultimately more alike than different, and the popular insistence that they sound completely different has more to do with what Freud called "the narcissism of small differences" than the headphones themselves. If you Google some variation on "HD650 vs HD600," you'll hear over and over that the 650 is "bassier" or "darker." Not really. There's actually very little difference across this parameter. Piano music presents an exception, but this is rarely what people think of as a bassy genre. There are two significant differences. The first is soundstage. The HD650's soundstage is wider, but that doesn't mean it can make a cramped recording sound airy. The HD600's soundstage is more intimate; there's less space between left and right channels, but it's not a huge difference, and I could see people preferring (or at least not minding) the HD600's tighter spacing. The most striking difference between the two headphones is in what I'd call "smoothness." The best analogy I can think of comes from digital photography. As an image sensor increases its sensitivity, it also increases its noise because you can't amplify a signal without also amplifying noise. There are two rival philosophies for dealing with noise: leave it as "grain" or smooth it out. Grain has its devotees, and the advantage of grain is that it preserves fine detail. The disadvantage is that past a certain point it becomes a distraction. The advantage of smoothness, meanwhile, is that it looks superficially nicer. The disadvantage is that when you look closely you won't see all the fine details. Like all things, it's a continuum of compromise. The 600 is the headphone to get if you value detail at the cost of an occasionally unpleasant grainy and even metallic quality to the sound. The 650 is the one to get if you care more about music than sound and don't care if your headphones sand down the sharp edges of your music a bit. Going back and forth between the two, it quickly becomes clear that the 650 is the stronger all-around performer: it sounds nicer on more recordings and across more genres. The 600, meanwhile, is the champion of a particular niche: good recordings with lots of micro detail. Want to be able to count how many times the skin of a drum reverberates after it's struck? Want to hear such fine vocal gradations you'll know how a singer felt during recording? The 600 is for you. Make no mistake: at its best, the 600 produces the most astonishingly detailed sound I've ever heard. Unfortunately, at its worst it sounds grainy, jumbled, and not particularly musical. I'm sorry to report that piano music sounds particularly off on the 600: low frequencies disappear and take the fullness of the keys with them. Vocals can sound oddly recessed, even far away. In general, the 600 seems to fare better with female vocals than male ones, and with strings over pianos. It's absolutely glorious for acoustic guitar, but then, so is the 650. The 650's great advantage lies in its ability to bring out vocals like a spotlight. They stand out so clearly and powerfully from the instrumentation that you'll feel like you're hearing your favorite songs for the first time. The effect is really quite incredible: it's like there's a special sonic column reserved for vocals and unpolluted by other sounds. Based on Sennheiser's own specs, the 650 has lower distortion than the 600 and it's clearly a more refined driver unit. Whatever the technical reason, the 650's background is pitch black: sounds rise from and fall back into a sea of silence. Be forewarned: a well-recorded vocal track through the 650 may bring tears to your eyes, and that's why I kept the 650 and returned the 600.