For someone who already hates the HD800, it is doubtful that the HD800S will drastically change their opinion. The HD800S is still a HD800 in that it is bright-ish, on the cold side and somewhat analytical… it still offers a kind of "austere" or cerebral listening experience. For the original HD800's diehard fans, I can imagine some disappointment. They'll probably miss the special excitement provided by the HD800 treble and instrument separation. Switching to the more “normal” HD800S would probably be like asking a cocaine addict to live only with clear water. I really think that people who already enjoy their HD800 with classical music only have no urge to buy a HD800S except if they are after more tonal accuracy and better timbres. I personally prefer the 800S but YMMV. For people who already liked the HD800 but still struggled with its treble and cold tone/weak mids, I highly encourage them to give the HD800S a listen. The new sibling could be a winner for them. For HD800 owners who don't want to lose money due to a low resale price but want to benefit from HD800S qualities, EQ and/or mods are probably the way to go. But, if you asked me what my advice is between a new HD800 and a new HD800 S, I'd honestly say that you should take the 800S.

here : http://www.tellementnomade.org/feedback-hd800s-s-comme-superieur-ou-pas/ .For people who are already familiar with the HD800, there is nothing surprising here: Same kind of box, same single ended cable, but a balanced cable has been added into the package. The connectors are now black.For the headphone itself, with the exception of the color scheme, nothing changed at all: Same frame, same pads, same grills, same dust covers… Even the name is unchanged on the headband. The only apparently new thing is the S/N. My HD800 is #17002 and my HD800S is the #493.The main change appears when we remove the dust covers: in the center of the web behind the driver appears the famous Helmholtz resonator:Compared to my HD800 without the resonator:What is a Helmholtz resonator? Thanks goes to Pietcux who linked to the answer in the HD800 thread: See this video which explains how this sort of resonator works.Measurements were taken on a DIY coupler + Mini DSP UMIK-1 microphone + REW. These measurements are only comparable with ones made on the same rig and shouldn't be compared to other measurements coming from other sources. No compensation was applied.As you can see, the measured FR can be significantly different depending upon the relative position of headphone and mic. Therefore, I have provided the entire group of raw measurements as well as the Average FR.HD800SHD800HD800SHD800All measurements show the most noticeable change between HD800 and HD800 S: The 6 khz peak is significantly reduced and the resonance at the same frequency is reduced as well. Besides that, all of the other differences are at best subtle…a bit more high mids, a bit less low mids and mid bass and a tiny bit more bass and treble extension. One noticeable drawback is that distorsion is less good in bass and especially sub bass area.Let's recall what Axel Grell told us about his new baby:“Sounds a tiny bit better, smoother treble, a tiny bit more bass and treble extension”.First time I listened to my HD800S, I immediately checked if the sibilance of the HD800 was still there. So, I put a Diana Krall track in my player .15s of listening were enough to allow me to understand that Senn fixed the 6 kHz. Compared to the HD800, the sibilance is mostly gone as sibilants are no longer exaggerated. For most of the people who listen to a lot of closed mic vocals, it will be much less fatiguing.Well, other than the 6khz “fix”, are there any other differences that I could honestly detect?The second subjective difference I heard was that mids and high mids seemed a bit more forward.Hence, there seems to be better presence and body for voices, guitars and some strings. So, I reflected next on what my measurements revealed. It seems to me that the 6 kHz is not the stronger enemy here. The most important thing to notice is the gap between 4 and 6 kHz. The HD800 exhibits a 15 db (!) difference between 4 and 6 kHz. Hence, there is the sensation of hollow, dead mids and overly present treble. The HD800S offers a 8db difference between 4 and 6 khz. So, logically and besides the absolute treble reduction, it seems that we can enjoy more mids and High mids with the HD800S. And this is, IMO, the greater benefit offered by the new HD800 S. I extensively compared both HD800 and HD800S to my HE-60 and if the HD800 is noticeably weaker than the old Baby Orpheus for mids, the HD800S is definitely a stronger competitor. A good aspect of those enhanced mids ( combined with the tamed 6kHz) is the better tonal accuracy and timbres. Instruments are more full-bodied and sound a bit richer, harmonically speaking. It's obvious when listening to the piano for example. In my case ( I listen mostly to instrumental Jazz and EDM and Classical), improvements in mids are really the main benefit of the 800S. Don't expect HD650, HE-6 or Stax mids though. "tiny bit better" as told us Axel Grell.In matter of bass, I'm sorry but I don't hear more bass. Neither did my mic, fortunately for me. Maybe my HD800 was already “more bassy” than the average HD800. Who knows? But as a matter of fact my HD800S#493 does not offer more bass than my #17002 HD800. Even more, my critical listening tests make me think that the HD800S bass is tighter, maybe cleaner and less mid bass centric. Extension seems to be actually improved. Overall, the HD800 and HD800S low register are very similar to my ears.That having been said and as I pointed out just above, for mids, I definitely think that -6 dB @ 6 kHz induces a new possibility to hear all the other registers. In one word, the smaller 6 kHz peak allows the other registers to blossom, bass included.Soundstage and imaging are IMO pretty much unchanged. The only exception that I would consider is in terms of instrument separation during very complex music ( mostly I heard it on orchestral stuff). For this kind of music I feel (more than I consciously hear, to be honest) that the HD800S isn’t quite as precise in delineating the separation between instruments, compared to the HD800. With the HD800 I feel like I can read along with the score, while I'm listening to music. With the HD800S I don't have that feel anymore. The positive aspect is that orchestral masses are a tiny bit more cohesive.Overall, in my opinion , differences between HD800 and HD800S are small, yet significant enough to mention.I don't see how one wouldn't see the HD800S as a superior headphone compared to the HD800. To my ears, the younger sibling is definitely more neutral and more of a reference headphone. That having been said, will the HD800 S always be the more enjoyable for you, me and everybody else? I don't think so.Let's consider the following examples:My final words are dedicated to Axel Grell and all Sennheiser Team. Kudos to you guys. You didn't fool us with the HD800S. In a headphone world where new TOTL champions cost an arm and a leg, you improved your current flagship without resorting to charging us an insane price for it.Thanks for that!