1. Sennheiser India was kind enough to lend me their HD 800 for a home demo, for an undetermined length of time. Knowing fully well that I won't be buying them. As I can't afford them at this point in time. So I'd like to thank you Sennheiser India for this kind gesture.
2. The demo unit is a piece from 2009. One of the first 250 HD 800 headphones that Sennheiser built. So it is the old version. And doesn't need more burn in either.
3. You'll be disappointed to know that most of the review was done with the Sonarworks Headphone Plugin. SW is a VST plugin that corrects the headphone's frequency curve to bring it as close to neutral as possible. I also enabled the Linear Phase option in SW alongside.
4. The reason for doing this was because in its stock form, the HD 800 was way too bright. And coming from the HD 650 I was unable to adjust. Nevertheless, the HD 800's sound fantastic even with SW enabled.
The Test Setup
Headphones - HD 800 (old), HD 650 (2013 - silver), HD 700 - All burned in heavily due to their age.
Amplifier - Project Ember Hybrid Tube Amp by Garage1217.com (with supercharger) -> Sylvania 6SN7WGT
DAC - Asus Essence One Muses Edition
Software - JRiver with Sonarworks for HD 800, HD 650 and HD 700 (HD 800 setting)
Music - Recent Bollywood
You should get ready to read the review. :)
Long story short, you'll be delighted to know the HD 800 blows away both the HD 650 and HD 700.
The HD 800 is clearer, cleaner, faster, more detailed, has much less distortion and just better all around.
In comparison, the HD 650 sounds muffled and distorted. It almost seems like a toy compared to the HD 800. Now. You may not like to hear this. But this is indeed the truth.
The only advantage the HD 650 has over the HD 800 is that it is a touch more musical and lusher. But the HD 800 is plain and simple better. And so much better than you'll never touch the HD 650 if you buy the HD 800 once.
After hearing the HD 800 for a few days, I'm finding it really hard to go back to the HD 650.
You name it. Breaking through congested passages. A larger soundstage. Better sound isolation. The HD 800 nails it nearly every time.
Even with SW, the HD 800 is a bit brighter than the HD 650. But no big deal. Without Sonarworks, yes, you'll find it hard to listen to the HD 800 if you're not used to a bright sound.
But that too has perhaps been fixed in the 2013 revision of the HD 800, perhaps.
Anyway, both headphones were used with Sonarworks.
And there isn't much of a contest.
You should take the HD 800 over the HD 650 for anything and everything. For all types of music.
HD 700 >= HD 800 >> HD 650
Both the HD 700 and HD 800 are very comfortable. The HD 650 isn't in the same league. Although it is pretty comfortable on its own.
HD 800 is cleaner and clearer. HD 650 is lusher. But HD 800 is in a different league altogether due to its lower distortion.
HD 650 has recessed treble.
HD 800 has forward treble.
With Sonarworks, I prefer the HD 650's treble over the HD 800's treble. But only because the HD 800 is still brighter. It is still better in every other way.
Again, HD 800 has less bass. But better bass. You know that!
The HD 800 feels like it has a 50-100% bigger SS as compared to the HD 650.
The HD 800 is clearly a big step up.
To wrap it up
I'd even say if they could take care of the bright treble of the old HD 800, it would be perfect.
The HD 800 deserves to be priced 3-5x the HD 650. IMO. Your mileage may vary.
And the above impression hasn't been formed over 10 minutes. Initially, I was a bit disappointed. But having heard the HD 800 for a while, going back to the 650 was shocking.
There is a big difference!
I recommend the HD 800 wholeheartedly. To everyone.
P.S. HD 700 vs HD 650 review - http://akshaytalwar.blogspot.in/2016/03/sennheiser-hd-700-sennheisers-queen-in.html
Also, updated the review on Amazon.com and Amazon.in, both 5 stars :)