Proven long time classics in the medium price range, the Sennheiser HD650 and Sennheiser HD600 remains as relevant as ever. I compared them to each other and also to the AKG Q701, which also is becoming a classic, being a slightly warmer tuned version of the AKG K701.
These three full-size open headphones were compared using three amplifiers: Violectric V200, Woo WA2 and Beyerdynamic A1. For the HD600 and the HD650 comparison I used all three amplifiers, but for the Q701 I only used the Violectric V200because the Woo WA2 and Beyerdynamic A1 are high output impedance headphone amplifiers. Using them with the low impedance Q701 gives sub-optimal results. The low impedance Violectric V200 on the other hand, is working good with all three headphones.
Track by track comparison
Higdon “Violin Concerto – 1726” with Jennifer Higdon
I love this piece of music, with its gentle violin and slow build-up. Sennheiser HD600 has a sharper edge on the strings, it has a better defined placement of instruments. With the HD650 it seems like there is more going on in the music, however. It feels less focused, but wider sounding. On the violin soloist passages, the HD600 is a clear favorite, but when the drama comes, I am not quite as sure on which is better. The thinner sounding HD600 looses a bit of musical weight. It is not that I can say I find the HD650 to have more bass presence , but it does have more of something.
In other words, the HD600 is airy, more neutral sounding, while the HD650 has that warmer and wider sound. Treble is more pronouncd on the HD600, which might account for quite a lot of the difference. Strangely, either one can sound a bit muffled compared to the other, depending on the specific passage. On the busy passages the HD600 feels more closed in than its bolder brother, whilst during the cleaner solo passages the HD600 seems just cleaner.
Plugging in the AKG Q701 gives me an even airier sounding experience than the HD600. There is more sense of air around instruments, it feels more exact, precise. Only in the bass region, the HD600 excels in comparison. The HD650 has an even bigger comparative advantage in the lower regions, and presents quite a fuller sounding experience.
Something just makes the HD650 more right with the WA2 then with the V200. But when the WA2 makes the HD650 more defined, the HD600 gets more of a “hollow” sound than with the V200. This is confirmed when I briefly switch the HD600 back to the V200, where the HD600 clears up again. Both the HD600 and HD650 is 300 ohm headphones, so I find it a bit strange that the HD650 should benefit so much more from the high impedance amplifier.
As with the WA2, the A1 just cleans up the HD650 here. It gets more defined and less diffuse, giving it slightly more bite and actually keeping up with the HD600 on its own domain. Still, some might prefer the lighter HD600 presentation, but I don’t.
Morrisey “Irish Blood”
On this song, the HD600 makes Morrisey’s voice and the general presentation, thinner sounding. It has what some might call a more neutral sound and maybe a better defined sense of space. It is creating less of a “sound of wall”-feeling than the HD650. However, the HD650 has a more natural tone to it, while still retaining detail retrieval. I prefer the HD650 here.
As for the AKG Q701, it has a much tighter soundstage. I also like its tonality better here than with the Sennheisers, but again the bass is not as satisfying, it just rolls off to much.
The difference with regards to slight “diffuseness of soundstage” I had with both of the Sennheisers on the Violectric V200 gets irrelevant on the Woo. The HD650 improves especially so on this point with the WA2, leaving the HD650 an even easier choice with the now.
Again, the A1 does for the HD650 similarly what the WA2 did, making me prefer it to the HD600.
Olga Konkova “As Before”
I like this song a lot. It has great percussive elements, and a politely beautiful female voice. The thicker sounding HD650 creates an atmosphere of warmth and intimacy, while the drier HD600 leads your attention slightly in the more analytical direction making each instrument stand out more. It is purely a matter of preference, how you like your “tuning”. I lean towards the lusher HD650 but have no problem appreciating the HD600 here.
With the Q701, there is more texture and air. In comparison, there is a more “closed-in”, a bit muted feeling with the HD600. Bass comes out pretty equal on this tune. The voicing is not very different, but I like the Q701 more.
Also here the tube amp makes the comparative advantage which the HD600 had on the HD650 in terms of soundstage diminish. But the HD600 works good on this track and with this amplifier, making it a matter of taste which of the Sennheisers to prefer.
Using the A1 amplifier also gets the HD600 sound very well on this track, making it hard to declare a winner. I especially like the open sound combined with the more punchy bass it delivers here. HD650 has the more of a lush experience, but for some reason, it is not enough for it to get favored by me this time.
Thomas Dybdahl “This Love is here to stay”
Again, the HD600 presents more of a tight presentation than its sibling. Instruments and vocals are slightly better focused, things feels tighter and tidier. Yet, the HD650 has that smooth warmth and the enveloping wall of sound feeling. I prefer the HD650, but not by a big margin, and I could just as easily landed on the other side of the fence here.
Even thought the Q701 feels more airy and precise, it lacks in the bass and the general feeling of intimacy which is better on the HD600. I find the Q701 a bit “thin” sounding for this track, especially compared the HD650.
On the Woo’s tubes, the HD650 truly shines, and offers a free flow of smooth musical goodness running through your ears. The HD600 on the other hand, gives me the impression that it is holding something back. It does impress me with its bass here, however – it is full, yet tight and actually on par with the HD650.
While the HD600 really have some nice qualities, the naturalness of the HD650 makes me prefer it yet again. HD600 is lighter, thinner and sometimes just a bit cannier sounding. But I am sure others could have ranked them differently.
This slow, jazzy tune is dominated by a picking guitar and some horns. It is a simple and clean track with few instruments and a low pace. The trumpet and sax has a much sharper edge to it on the HD600, the perciussion feels snappier. HD650 adds fullness to both the horns an the percussion. The electrical guitar has more flesh. On this track I really prefer the HD650 for its way of making instruments sound full and delicious.
The Q701 gives you a bigger room and more texture to the sounds, but the slightly more fleshy sounding HD600 is also very enjoyable, so it is hard to pick a silver medalist – but HD650 is clearly the favorite.
The crispiness of the HD600 is really enjoyable, and while it is not a big difference between the tube amp and the V200 for the DH600, I prefer it on the WA2 here. The HD650 is delicious as always, but the trumpets aren’t as crisp sounding. While enjoying the HD600 I’d still find it hard to give up the HD650 smoothness.
As with the WA2, this amp favors the HD650, and for the same reasons it makes me prefer them, although the HD600 also sounds great. Just not as delicious.
Lamb “Scratch Bass”
I was really expecting the HD650 to perform this bassy electronic track in a full and enveloping way, I did not get disappointed. The HD600 delivers good and solid bass – but the treble sticks out more, in a slightly annoying way. If I were mixing this track, however, I might prefer the HD600 because it is easier to identify separate elements, but for pure listening pleasure, the HD650 is right were it is at its best.
A bit surprisingly, this bass-driven track sounds quite good on the Q701. It has the usual amount of air and detail, but since the bass is so pronounced on the recording, it really comes through – even on the Q701. But the 600 has more bass, and this is electronica. Neither of them are bassy, but the Q701 just isn’t made for electronica, I guess. So I am preferring the HD600 more than the Q701, and the HD650 the most.
Breaking the pattern on this track, the WA2 amplifier seems to “loosen up” the HD600 a bit, making it more enjoyable than with the V200. But HD650 is still even smoother and even more enveloping.
Again, the HD600 is really enjoyable here, and probably with a more spacious presentation than the HD650, yet having similar mid-bass performance, making it a fun listen. HD650 is less spacious but again, more enveloping.
Since all the amps I have tested are quite a bit more expensive than the headphones I tested, I tried some tunes from the only budget amp I had at hand, the Nuforce iDo. The same sound signature pattern was revealed however, the HD650 is still fuller and smoother than the HD600. From the iDo I really the always felt the HD650 sounded better, maybe it just is a better match with the iDo. I also tried them with the HTC One, which made a decent job, but very far from ideal. These are high impdance and low sensitivity cans, and even though you get the volume high enough, a cellphone won’t give you the voltage swing you need to get the dynamic headroom.
The HD650 is clearly the smoother of the two Sennheisers, with a warmer sound signature. It plays the music in a full bodied and natural way that has a very unique appeal. The HD600 gives more of a neutral presentation, but in the global perspective it isn’t that far away from its sibling. They are clearly coming from the same place, just in different flavours. With regards to objective parameters such as detail retrieval, precision etc I cannot say that one is significantly more resolving than the other..
With regards to amplification, I found the HD600 often better with the V200, while the HD650 was clearly better with the Woo WA2 and the Beyerdynamic A1, all depending on the tracks I played. It seemed like the WA2 “tidied up” the HD650 soundstage a bit, which was one of the areas were the HD600 had a clear advantage on the V200. The WA2 had the opposite effect on the HD600, and somehow it was taking off some of its forwardness. With the V200 I sometimes experienced the HD650 as having a slight “boxy” or “fuzzy”presentation, especially with vocals. I attribute this to a slight diffuseness soundstage. This was no issue in that regard with the WA2 and A1. Since the V200 has an output impedance close to zero, and the WA2 and A1 are high output impedance devices (80 and 100 ohms respectively), I suspect that the HD650 might be better off with higher output impedance devices than HD600 (however, I must rush to add, that there are other low impedance amplifiers that are great with the HD650). So, summing it up: For HD650, get the Woo WA2 or the Beyer A1, for the HD600 and the Q701, get the Violectric.
Compared to the Q701, I really find the Q701 to be significantly better for acoustic music, especially classical pieces like string quartets. But as an all-rounder, the HD600 seems like a better choice. Loosing some air and precision, but gaining on bass quantity and intimacy. HD600 gives you a nice blend of HD650 and Q701 in one package. What you loose on this all-in-one is the extreme delicious smoothness of the HD650 and the superb imaging and airiness from the Q701.
Jennifer Higdon: “Violin Concerto 1726” played by Hilary Hahn, Royal Liverpool Philharmonic Orchestra & Vasily Petrenko
Morrisey: “Irish Blood” from “You Are the Quarry”
Olga Konkova: “As Before” from “My Voice”
Thomas Dybdahl “This Love is Here to Stay» from “What´s Left Is Forever”
BMX: “Snoopy” from “Bergen Open”
Lamb “Scratch Bass” from “What Sound”
HD600 – 300 ohm, 97 dB/mW
HD650 – 300 ohm, 103 dB/mW
AKG Q701 – 62 ohm – 105dB SPL/V
Woo WA2 using TS5998 tubes