HD6XX - noob questions

I need to ask a question - when people talk about the HD6XX, is it specifically the model from Mass Drop, or is it the 600 series as a whole? Reason I ask is so often I see the 6XX referenced as the “reference” to compare all others against. Even though from what I read I do not think that they would be my cup of tea (I like bass and too much treble turns me off), I am thinking I just need to pick up a set to get an idea for myself what everyone’s going on about and be able to better judge for myself. Which one do I order - HD600, HD650, HD660 etc. etc., I prefer to Amazon as I am not a dropper but might if necessary.

Edit - for some back ground these are HP’s I have:

  • Koss KPH30i (never have worn got them long time back to use as a headset for video calls, but was given a Plantronics set by the office and so I’ve never opened them)
  • Corsair HS50 (I don’t game with HP’s but they were a gift, so I have them)
  • Phillips X2HR’s
  • Sivga 004
  • Sivga Phoenix
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The 6XX is basically a 650, but substantially cheaper.

It’s not one of my favorite headphones on lower priced amps, it’s a bit of a one trick pony, it has spectacularly good midrange, and not much else. You have to be able to get past the lack of bass to really appreciate them.

Where they 650, 6XX and 600 become interesting is when you pair them with a decent valve amplifier, the rather severely elevated impedance at low frequency and in the treble region, result in those regions being elevated on a tube amp, and it can sound quite special.
I have a lot of headphones over $1K, still use the 6XX on occasion.


Good information - So I may not be doing myself an injustice by not having a set? I don’t have any tube amps, and I am relatively new still working off a starter Dac/Amp (JDSL Atom stack).

O and thanks @Polygonhell - for clarifying that the HD650 is the equivalent of 6XX

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To expand on Polygonhell’s reply, the HD 600 was released in 1997 and quickly gathered a reputation as being a breakthrough in frequency response accuracy (for that time). As Polygonhell has said, by today’s standards it’s only so-so in all other areas, unless you use it with tube amps or certain expensive solid states. The HD 650 was released a few years later with a bit more bass and a bit less upper mids, apparently to address criticisms of the HD 600. But the headphone community was divided on that, with quite a good percentage preferring the HD 600 over the 650.

Based on its frequency response measurements your X2HR looks as close to accurate as the HD 600 or 650. The only reason to get a 600 or 650 now is not accuracy or sound quality but simply to know what a reviewer or forum commenter means when he compares some other headphone to one of them. And, yes, the 6XX is widely thought to be an 650 on the inside with cheaper grade plastics used in its outer construction, supposedly to bring down the cost.

Sennheiser keeps on trying to kill off all three models, even announcing a couple years ago that they were discontinuing the 600 and 650, since everyone should prefer the new and “better” HD 660S. But the older models just keep on selling. The new HD 560S is their latest attempt to kill the old models off. Their pitch now is that you buy the 560S at a lower price point or the 660S at a higher price point and either will be better value than the 600 or 650. Hope springs eternal.

Oh yes, almost forgot. There’s yet another reason for the “reference” designation. This takes us a bit into the weeds. Sennheiser stated in the product manual that the HD 600 was tuned to the then-new diffuse field (DF) frequency response reference. That was actually only half true. Diffuse field is one theory for frequency response accuracy when listening to live sound. The HD 600 is actually tuned to DF modified by the clockwise/warming tilt that room acoustics has on loudspeakers playing back recorded sound in a good room. This is a very good thing, since we mostly use headphones to listen to recorded sound, not live, but they just didn’t bother to mention that part. So a whole generation of headphone enthusiasts happily believed they were listening to the pure unadulterated goodness of DF – with it’s ruler flat bass and whopping 15.5 dB of upper mids – and now obstinately equate DF with audio neutrality.

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If they announce that they’re killing the 600 and 650, the stampede to get the last remaining ones will be biblical lol.


Lucky then i got 2 pairs. lol
On the time of apocalypse event, there might be few for sale, starting at 1000$ :drooling_face:


A friend has offered to let me borrow a HE400I - I know it’s not in the class of a 650 but, I am going to hold off and any purchase for now until I get some experience with the HE400I. Looking forward actually to see what I’ll learn when stepping out of my safe zone of darker leaning & bassier HPs.