[MuppetFace]

  I disagree with the bass (wondering here especially since most people won't agree with you here, please check your replacement model for its bass again) and treble impressions. The treble is not smooth but still far from a PRO Ultrasones or a T90 (and still, the HD 800 has its own treble peak flavor, a toss-up in this case) while the bass presence, impact is noticably more/better than the HD 800. I agree on the extreme seperation and the superb imaging and soundstage. In general I consider the K812 more genre-proof than the HD 800 and ultimately (also thanks to its bottom end) much more universal if you also watch movies or game. 

 
I sincerely doubt my impressions for these will change due to the crack issue, as so far it hasn't gone past the outer surface of the cup and where it connects to the frame. It does not effect anything inside the cup at this point.
 
The comments about bass versus the HD800 were qualified in my impressions. I said that I simply disagree with those who say the HD800 is lacking in its bottom end response and, when driven properly, I feel the HD800 has some of the best low end punch (NOT quantity) of any dynamic headphone out there. When folks tell me the bass on the HD800 is weak, I just have to assume they aren't amping it well. The HD800 is an incredibly picky headphone, and I would say the majority of the rigs I've heard it on don't do it justice.
 
The bottom end of the K812 is very satisfying, don't get me wrong. Unless you're looking for something specifically for bass performance, I think the K812 will not disappoint in that regard. However I'm a bit overly-picky when it comes to the sense of physical impact in my headphones, especially as my references for this are---in my opinion---two of the best performing headphones in that regard: the Abyss and HD800 driven from a Liquid Gold. That I would even think to compare the K812 with these headphones though speaks highly of the K812; I think it's in the same league, just with its own unique take.
 
As for treble, again, my comments are in purely relative terms: I'm not hearing the same peakiness as the stock HD800. It's quite possible the peaks on the K812 just aren't as bothersome to me as the HD800's, sure. I'm not trying to suggest that the K812 has an Audez'e-like smoothness to it up top or anything though. In my impressions I tried [as best I could] to indicate the balancing-act that was going on with the K812. I went back and clarified that a bit.
 
I'm totally willing to revise my impressions if I somehow get a much bassier and harsher sounding K812. Then I will promptly send it back to AKG or re-crack it and advise others to do the same on their sets as a mod LOL. Seriously though, if others disagree with me that's a-okay. I feel no pressure to try and retune my impressions at this point having spent a good deal of time and energy trying the K812 on different rigs. Sometimes language can be tricky when talking about this stuff though, and I'm pretty sure we'd actually agree more than it might appear if we get past semantics.

 

[JWahl]

Thanks for the impessions, Muppetface.  Pretty wicked front end also so good to hear it can scale as well.  Ive been impressed with my K712 as a stopgap despite being very critical of the older 7 series.  I am also eyeing the new Hifiman HE-560 as well but might have to find a way to afford both.  Though I will probably wait til the price drops or I can talk a dealer down to around 1100 or so.
 
Would you say the general presentation leans more towards a "fast" sound like open AT's or something more euphonic and resonant, or something in between?  I do like a certain sense of speed which I felt the HD800 did well enough in comparison to the AD2000x that I didn't need to keep the latter.

 

[FritzS]

If anyone understand German
 
Kurzreview Stax SR-009 vs. AKG K812 Pro vs Stax Lambda Signature
http://www.open-end-music.de/vb3/showthread.php?t=7004

 

[TheDuke990]

  I disagree with the bass (wondering here especially since most people won't agree with you here, please check your replacement model for its bass again) and treble impressions. The treble is not smooth but still far from a PRO Ultrasones or a T90 (and still, the HD 800 has its own treble peak flavor, a toss-up in this case) while the bass presence, impact is noticably more/better than the HD 800. I agree on the extreme seperation and the superb imaging and soundstage. In general I consider the K812 more genre-proof than the HD 800 and ultimately (also thanks to its bottom end) much more universal if you also watch movies or game. 

 
But only the sub bass has more impact compared to HD800.

 

[Maxvla]

Fully agree with MF's comments based on my audition of the K812 and my long standing experience with the HD800 on multiple amps. The K812 is an impressive return to relevance from AKG, but IMO, it's a touch behind the HD800 in a couple areas. The biggest is soundstage and imaging. It's hard to beat angled drivers with non-angled drivers. I would say the K812 is probably my second favorite dynamic headphone, currently.

 

[Trance_Gott]

IMO 812 is a touch better as HD800 in every area except size of the soundstage which is also big with superb imaging.
But that's just my 2 cents. I hear mostly Prog Rock and Pop. People which hear Classic maybe prefer the bigger soundstage of the HD800. But with my music the Senni sounds a little bit boring and tend to nerv in the highs (anyway with Lehmann BCL, I don't tested them with a tube amp). I never liked the HD800 and preferred the T1 before the 812.
Technically the HD800 and K812 are the best dynamic headphones!

 

[third_eye]

I heard the 812 at NAMM this weekend. It seemed very nice and I look forward to spending more time with it soon in quieter conditions.

 

[Kyle 491]

I disagree. Their biggest concession to the HD800 is transparency. They have too much ringing which is hard to ignore when listening at higher volumes. Previously I erroneously attributed this flaw to the mastering of the "Time" test track, rather than the headphone itself, but after listening to the same master on the HD800, I never experienced the cacophony of excess ringing bells as I did in the intro of song, even at volumes >100db. I don't think they are suited for high-volume listening, despite having such a nice tonal balance. Look at those 100db THD measurements on Tyll's graphs, and how long it takes the impulse to settle down on the Impulse Response graph. Hardly exemplary.

 

[Trance_Gott]

Volume of 100db? Sorry, but these are unlistenable volume levels! I tested them very very loud. No ringing at all with my AKG K812!!!

 

[Kyle 491]

I don't listen at such high volumes normally, but its not uncommon to hit 100db dynamic peaks in the music I listen to test headphones. For the asking price, a flagship headphone driver should be able to maintain its composure at higher volumes. That speaks to the level of engineering skill in the design.

 

[Acix]

  I disagree with the bass (wondering here especially since most people won't agree with you here, please check your replacement model for its bass again) and treble impressions. The treble is not smooth but still far from a PRO Ultrasones or a T90 (and still, the HD 800 has its own treble peak flavor, a toss-up in this case) while the bass presence, impact is noticably more/better than the HD 800. I agree on the extreme seperation and the superb imaging and soundstage. In general I consider the K812 more genre-proof than the HD 800 and ultimately (also thanks to its bottom end) much more universal if you also watch movies or game. 

 
 
The bass sound separation of the K-812 is notable better compare to the HD-800?
 
As well what up with the treble, tizzy as the HD-800/T1?

 

[up late]

is the k812 made in Austria or China?

 

[JWahl]

Fully agree with MF's comments based on my audition of the K812 and my long standing experience with the HD800 on multiple amps. The K812 is an impressive return to relevance from AKG, but IMO, it's a touch behind the HD800 in a couple areas. The biggest is soundstage and imaging. It's hard to beat angled drivers with non-angled drivers. I would say the K812 is probably my second favorite dynamic headphone, currently.

You, too?  Wow, I'm shocked.  I remember you not being a huge fan of the T1 before so even this small concession to the HD800 is a compliment IMO.  The retail price does make it harder to bite since the HD800 has dropped in price.  The HD800 is currently the favorite I've owned, planar or dynamic.  I think I could accept a small concession in soundstage and imaging with the slightly more "musical" and well balanced presentation that has been previously described.
 
Now I'm curious of how they stack up to the big name planars.

 

[DefQon]

is the k812 made in Austria or China?

The former.

 

[MacedonianHero]

  The former.

....Holy Roman Empire.