Nice review. I am Dynamic all the way. 

Excellent review, thanks....
How was the "SCHWEEEEEEEET" on the "S"s in comparison if you had a chance to listen to the "Junkies famous song Sweet Jane" ?

I avoided the 800 and only recently took the plunge with the 800S and I really like this headphone. It seems to straddle the world of high detail and musicality with aplomb. I enjoy it from either my SS or OTL amp. I am not such a purist that I can't enjoy some well thought out 2nd order harmonic distortion, so Tyll aside, I like the effect. Nice review mate.

@Rob80b Funnily enough, I didn't think to listen to it! It only came to mind after I decided to talk about the HD800. 

Tried the HD800, tried the HD800S, got the HD800S. It's surprisingly sensitive as well - I'm using a Vali 2 on high gain (low gain makes everything too muffly and soft - banjo strings should have a sharp tone to them, for instance), and I have to lower the variable output on my DAC to compensate. The knob on the Vali 2 is pretty much stuck at the 10:30 mark. I'm playing around with Goodhertz's Canopener and Midside plugins, and they do good things for the overall soundstage. No more blobbiness. I'm using Tyll's EQ settings (bass boost from 20-40hz, bit of a mid hump at the 1k range, and 5k-onward treble cut).

Amazing review Currawong! How would the HD800S do with an AMP like Schiit's Mjolnir (tube)? You stated that they quite easy to drive, but i've heard other wise. I have not given them a real try yet.

Good review. It's a great set, only drawbacks is sounding thin with some recordings and being extremely vulnerable to any noise, including low volume hum from fans, which drowns a lot of low level detail. They're nice but those aspects (combined with requiring amping) make them less flexible.

If you have the right amp (yes, it does matter for the Senn), they are quite incredible. They do scale considerably from mid to highend amplifier especially driven in balanced mode.  They don't sound that "thin" out of my ECP amplifier.

Thanks for sharing this review, Currawong! 

@Curawong maybe I'm dense, but I couldn't find a mention about the stock cable degrading the sound, would you elaborate?  Also, do you mean the balanced or the single ended stock cable?   What amp did you end up settling with the HD800S.  Thanks for the review, cheers.

I'm glad that you notice a design similarities between the Qualia & HD800.  Of course, the Qualia MDR-010 was crated back in 2004.

I'm really waiting HD850 real soccessor of HD800s. must be ultra low THD exciting!

Nice review, But I think in couple of places 800 and 800s are misplaced.
"when Sennheiser's HD800s were introduced at CES on the 8th of January 2009"
"The HD800s have a peak at 6.3 kHz"

IMO, the headphones take a while to break-in, plus I made a custom 20 ft cable that also has takin time to sound its best.    Now with over 250 hours on my 800S they sound sweet with all the Bass I need provided by my Oppo HA-1 DAC/Amp with Balanced connection.

@MuZo2- By "800s" he means plural, as in "the eight hundreds". He uses capital S (800S) when he means the S.

apologies, but that was really confusing while reading.

Thanks for mentioning that Macy Gray album it sounds amazing

@MuZo2  @VandyMan I've been constantly debating with myself as to whether I should simply refer to headphones in the singular (probably grammatically incorrect, but more practical) or in the plural. The HD800 S name then ends up making that confusing. I changed to the singular form half way through, so I'll fix that.

Have you tried Sorrodje's Super Dupont resonator mod on the HD800?  I had my HD800 modified to eliminate the connector and Sennheiser's poor internal wiring by directly hard wiring 19 gage Wireworld Eclipse OCC copper cable to the driver input.   I also put the super Dupont resonator that Tyll mentions in his HD800S review in my HD800.  The cable and the SDR mod address the lack of warmth and 6kHz spike without having any negative affects that I can detect.  I recommend HD800 owners to check out those 2 mods.  I think these mods go a long way to improving the performance of the HD800.  Previously I tried the Anax mod but I removed it because I felt that the soundstage was reduced and it didn't address the 6kHz spike in my opinion.  I agree with you that the Sennheiser cable makes for an unpleasant listen.  Any pure OCC copper cable will be an improvement over the stock cable.

A very interesting review