Pros: Comfortable, never fatiguing, and with the right recordings the lows can really shine
Cons: Treble a little too slow, bass could be a smidgen punchier
I moved from IEMs to full sized headphones, and the HD650s were my first real investment. My first "real" audiophile big can was actually the Audeze LCD-2s, but I never had proper amplification back then. As a result, I never experienced what the LCD-2s could actually deliver. I ended up selling my LCD-2s and then going back to IEMs, all the way until this year when I took the dive and tried to buy the safest, most solid cans set I could. I went for the most famous, solid buy and went hunting for the best amplifier match. This, of course, led me to the Sennheiser HD650s.
My chain ended up looking like this:
Foobar2000 with WASAPI Event, FLACs > Schiit Modi DAC > Bottlehead Crack + Speedball Upgrade (with Tung Sol 5998 Tube) > Sennheiser HD650s (Silver driver)
I have been beating myself up over whether to rate the HD650s with 3.5 stars or with 4. If I really could choose, it would be a 3.75/5. However, I am marking in a very difficult manner; I have tried out a handful of good headphones and so it would take a lot really wow me. A 4-star rating would be a "wow" but with a few reservations here and there. So, a 3.75 is a very good mark; it is just short of a "wow." The details with the little green bars are a little more informative of the way I feel about the HD650s (EDIT, the green bars seem to be very inaccurate when I save the post. Instead, here are the scores: Audio Quality (B+), Comfort (A), Design (B-), Value (A+).) With that in mind, let me expand on my experience with the HD650s.
At first, I thought the HD650s were absolutely dreadful. The bass was extremely floppy and bloated. The lows were absolutely non-existent. Treble and highs were slightly tinny, but mostly just very unrealistic and slower than a snail (it seemed like there was long decay on treble and highs). I was very concerned and posted in the HD650 appreciation thread with my impressions; I wasn't sure if I just didn't like the sound, or if there was something wrong. And, given that the Crack is a DIY amp, I also went on the Crack forums to try and figure out if there was a serious mistake.
Well, there was a big mistake. The headphones and the tubes in the amplifier were not burned in. I'm a very scientifically inclined person, and so I have always been very skeptical of burn-in. But after my experience with my setup and burn-in, I am now a 100% believer. The difference was so enormous that I am not sure how anyone could deny the existence of burn-in, at least for tube amplifiers (I don't expect it to be very real when it comes to solid-states) and dynamic phones like the HD650s.
After about 30 hours of burn-in with pink noise and various music at slightly higher than listening volume, suddenly the lows appeared. The bass tightened up tenfold, and the treble lost its sibilant ring. The mids, for the most part, sounded the same, though they were never really atrocious to begin with.
THE DESIGN & COMFORT
The design of the headphones is simple, but they look professional. The biggest problem I have with the HD650s is their construction material. I was very disappointed to find out that the headphones are made out plastic, and plastic all over. This doesn't mean that they're flimsy, but I wish there were more metal on the headphones. If you look at the picture of the HD650s on the HeadFi reviews section, they look almost metal. The reality, however, is that they're almost entirely plastic and a lot lighter than you expect. The headband comforter is also not premium; for instance, the headband on the HD598s seem higher quality.
The clamp force on the headphones is great. It's a little strong, but it's better to be strong and loosen over time than be loose from the get-go. The earcups are quite large and will fit around even the biggest of ears.
My reference point has primarily been my experience with the Shure SE535s, Earsonics SM3 V1s and the Westone UM3X in-ears. In terms of speakers, a set of JBL LSR2325p studio monitors. The rest of my can experience has been with lower end headphones (like the ATH-M50s), Shure SRH750DJs and a bunch of lower end Sennheisers. Indeed, these comparisons are not always fair; each is a different class and will present sound differently. With that in mind, I will try to present my impressions as transparently as possible.
The sound of the HD650s is really good; however, I would hesitate to call them spectacular (though they are spectacular to people who allegedly enjoy the sound signature). When people say that the HD650s are laid back and mellow, they really are not kidding. I always had a hard time imagining what they meant. The closest thing to "mellow" I could think of were the Sony MDR EX1000s, but the Sonys are more "romantic" than they are "mellow."
What I found "laid back" and "mellow" to mean is that nothing is really forward or present with the HD650s. Some people really value this aspect of the HD650s. For me, it did not really hit the spot, but I can respect and appreciate it regardless. Nothing really stands out with the HD650s: everything sounds good, but nothing really jumps out at you as being their focus, or even as being superb. This makes for a mellow and relaxed sound. You will never fatigue listening to the 650s because nothing is being pushed on you. With the 650s, the music is presented gently to your ears, and it makes very good for "just listening" and going about your business. It's probably the best headphones to have on while casually listening, but I believe you will be moderately disappointed if you would like to really close your eyes and feel lost in the sound or if you have high expectations about being swept off your feet. This is because with the way the HD650s present the music, you just know that the music is being played at you and that you're listening through a pair of headphones (albeit a really good pair).
The bass is very, very good. I just wish it could be 10% punchier, but it does a very good job. However, the HD650 bass really depends on the track. On well mixed and mastered tracks, you will get a very nice bass. It is very controlled and, for the most part, feels "just right." It's some of the best bass you'll be getting if you're not a basshead, and if you're listening to music and don't explicitly want to be jumping around and dancing. I really, really enjoy the bass for any kind of listening except for dance music; it does its job fantastically. However, I believe if it were just 10%-15% more punchy, the HD650s would really be brought more to life. Then again, the phones are supposed(?) to be laid back. It's like being hit with a harder pillow; it's not too soft, and it's not too hard. It's controlled, disciplined and almost at the perfect line between whooshy and punchy.
I believe the lows are the absolute best part of the HD650s. If you get a good recording, the lows are just magnificent. Bass guitar sounds just wonderful on these headphones. It sounds very, very natural and even electrifying at times. With the right racks, the lows really carry the track forward and keep you slightly bobbing your head or tapping your feet. This is really where the HD650s shine.
I think I have to admit that I'm a little mid-obsessed. If you look at my previous IEM collection, you can tell that I bought IEMs I believed would bring me great mids. The HD650s, although it might be unfair because of how much I like mids, did mids just fairly. I mean, compared to anything else the average person has heard, they certainly are very good. But I do not think that the mids are as well refined as the lows. Keep in mind, though, that some people like the mids the way they are and don't like forward mids, so it is all up to you. That said, here are my personal thoughts on the mids.
1. I believe the mids could be brought a little forward. Even if the headphones are not supposed to be uber mid-centric, I believe the mids are just 20-25% off the mark in terms of their closeness. Sometimes a track that is normally really engaging just isn't on the HD650s, and it's because the mids just aren't present as I believe they ought to be. (Then again, personal preference plays a big factor.)
2. The mids could be warmed up a bit only because voices didn't seem realistic or natural. Compared to what I've heard on the SM3s and especially the Shure SE535s/530s in terms of vocals, the HD650s made vocals sound like they were just being played at me. I didn't feel like I was being sung to, which makes me very sad because I like it when Taylor Swift whispers into my ear.
3. Some people argue that being too forward on anything isn't "natural." But I don't know what is more natural than hearing a singer as if the singer is speaking to you, given that's what it sounds like in real life (the epitome of natural). I could not feel my singer's breath, and I knew that there was a mic between me, the singer and the music. If you've ever heard the SE535s, that's how vocals ought to be done; they are so lush, smooth, caramel and real that you sometimes get goosebumps from good recordings.
4. If you're not vocal-mid focused, then the mids will do just fine. In fact, guitar sounds great through the HD650s. B.B. King sounds great on the right recordings, as does distorted guitar in classic metal bands (e.g. Judas Priest, Iron Maiden, etc.) and groups like Paramore. However, the vocals just isn't this headphone's strength; I tried Grammy winning engineered albums and very well reputed vocal albums (including jazz vocals, etc.), and none of it stood out as being outstanding. It's just a fair contender.
The mids, as they stand, are pretty laid back. You get fairly good detail, but there isn't a lot of body to the mids. This is perfectly fine for instrumentals, orchestras and a lot of other music, but it is not good for very vocal centric music. The 650s are still quite textured, and so the mids aren't by any means bad. Guitar, especially in classic metal and rock, sounds great. I love guitar through these headphones. However, despite what some other reviewers might say, coming from someone who has a history of hunting for mids, I do not believe the 650s hit the mark on mids if you are someone who listens to a lot of vocals. For instance, running Adele, Taylor Swift, Hayley Westenra or lower voices like John Mayer or Diana Krall(sp?) through any of the mid-kings would be a reliable hit. However, none of these really stood out with the HD650s.
This is all to say, however, that "Kind of Blue" by Miles Davis sounds absolutely extraordinary on the HD650s. In fact, I believe it is the absolute best recording I have heard through these headphones; it has yet to be bested. The saxophone is breathtaking. But Miles Davis wasn't known for his vocals, and none of the tracks offer any. But that's why the HD650s did well with it.
HIGHS AND TREBLE
With my first Raytheon 6080 tube, there was a lack of clarity up top and in the treble in general. Switching over to the Tung Sol 5998s, the highs and treble came out. The highs are never sibilant, but aren't very energetic either. Overall, they are highly satisfactory for most purposes, but I believe things would really come alive or be taken to the next level if you could squeeze another 15-20% out of the HD650s up top. Then again, the HD650s aren't known for an energetic or hot-top end.
The HD650s are not very analytical, but it is enough for you to understand a bad recording for a good one. However, it is forgiving enough to keep everything tolerable, even if not blissful at all times. I don't really find myself complaining about the treble or highs, but I also don't find myself being blown away by them either. The "air" of the HD650s lends great to shimmery sounds, however; it kind of sparkles just enough for you to smile.
SOUNDSTAGING & OTHER
The soundstage of the HD650s is all right. Some people have described the sound as "three blobbed" and I understand why that would be said about them. The HD650s sound like they have a medium-small room soundstage. The instrument placement in the recordings is good, but I sometimes crave that BIG sound. I thought the HD650s would deliver on that front, but they really aren't that big. The suondstaging is by no means bad, but again not spectacular. The sound is not congested, but you can tell that the music is being played through headphones, rather than feeling like you're there with the music.
Instrument separation is not particularly high (but that doesn't mean the HD650s lack a lot of resolution). I think the 650s like to give one coherent, gentle sound rather than ripping everything apart like the UM3Xs or completely punching you with a tidal-beam of sound (as on the SM3s). I think the level of resolution is perfectly fine. I think it could use a nudge more just because, but there is nothing negative to be said here! But this is a good segue to the next point:
You can nab a mint pair of HD650s on the secondary market for extremely cheap. Low to mid 300s before shipping. That is an oustanding deal for such a solid pair of headphones. I bought a winter coat more expensive than my HD650s today, which just helps put everything in perspective.
If you noticed, most of my criticisms were wanting 10-25% more out of everything. But I suspect that's what is supposed to be delivered by the next level of headphones (HD800s, LCD2s, etc.) which cost a lot more. For the price, the HD650s are very well justified. And, the truth is, the HD650s should be a staple of every headphone collection (if you can afford to keep it)!
Overall, a very good headphone, but seldom spectacular (except in the lows if you hit the right recording). The headphones sound laid back, and maybe that was Sennheiser's goal. But, if I dare say, perhaps it sounds laid back because it does everything just "well," but never anything more. If you took the 650s and somehow could extract that extra 10-15% from it, it would be absolutely outstanding. The phrase "So close ... yet, so far away" describes my HD650 experience quite aptly.
The lows are its greatest strength, followed by the bass. The mids leave you wanting a lot more if you listen to vocals, but can deliver from time to time if you like guitar or non-vocal music. Dance music and electronic music, however, is really off the table. Electronic music is what I listen to the most (not anymore, though, just because of my setup!), but I just don't think electronic music fits well with the HD650s because electronic music is, by nature, a high energy genre, and the HD650s are anything but energetic. They are not energetic anywhere along their sound, and I think that is both what makes them so charming, but is at the same time their downfall.
The HD650s, by being so close yet so far away, is just a great, solid listen. It really is the introductory audiophile can par excellence. It does everything well, but not well enough so that you know there is for sure better out there. If you could just push that extra bit of work out of it, the 650s would really be stellar. But, hey, maybe it's just my amp and DAC; perhaps you could get the extra work out of them if you hooked up some multi-grand amplifiers... Then again, if you're fooling around with something like a Zana Deux, Leben or Wine Audio, you probably shoudn't still be listening to the 650s!
Very good, but seemingly always a tad short of spectacular.