HD800S 75th Anniversary Edition vs HD820 on Liquid Platinum fed by MXDAC. No EQ. First few days impressions THE TREBLE: Tie HD800S keeps up the brilliance of OG HD800 (owned this a few yr ago), but dials it down to the level where it rides the cutting edge of being brilliant yet not irritating like the OG HD800 can be. HD820 takes it down a notch further from "brilliant" to "superbly detailed". So if the HD800S was too much treble for you, the HD820 is tweaked bit downward a bit further; but for some this may be a downgrade I personally would give this to HD800S but I can see some give it to HD820 if they are annoyed by "brilliance" sparkle or super treble sensitive, so preference is where its at here. THE BASS: Winner HD820 HD820 is overall more satisfying. The HD800S has very satisfying bass as well, but it just doesn't dig as deep as HD820 and thus HD800S is just a bit less satisfying on some material. Maybe you'll like the HD800S just as much or better if your music has no deep bass, but I find most music I listen to does. THE MIDS: Winner HD800S (biggest advantage) HD800S has more lush mids and feels more emotive. HD820 still quite good, but not HD800S level. HD820 is two steps down from "lush and emotive" to "very impressive". The HD820 is less "live" sounding. THE SOUNDSTAGE: Tie Now this was even a surprise to me. A closed back at dead heat with one of the most expansive open backs? Yes. Definitely. WARNING: AUDIOPHILE BS DESCRIPTORS AHEAD. But, best way I can describe. The HD800S is like walking out into a beautiful pasture in the bright sunlight, with sound showering down all around you, your music happily mixing with the natural ambience The HD820 is like taking a seat in a concert hall with spectacular acoustics, and you are the only one in the audience - then the performance starts. In both cases, the soundstage is incredibly impressive and all around you. But they are different. At different times, with different content you may prefer one or the other. Both are interesting in their own way. and I would say it also depends how you are feeling in terms of mood which one you might prefer at any given time. There is no clear winner given the advantages and extremely impressive technical executions of both approaches. HD820 a good headphone to drown out the world with, HD800S a good headphone to let it all in. ISOLATION AND LEAKAGE: Winner HD820 (biggest advantage) Well this was pretty obvious. The HD820 isolates pretty decently and leaks much less. Any noise at all in in environment and HD820 is easily the better choice, while not noise canceling it does enough to kill off background noise pollution. Not much else to say. FIT AND WEIGHT: Winner HD800S Again pretty obvious. HD800S is less bulky, stays on the head better, and weighs less. Because it doesn't need the extra weight of a closed back, of course; makes sense, and the HD800S fits better as a result. Additionally, since the HD800S cups are smaller, they are better for when you want to rest your head back on a chair or pillow. INITIAL FEW DAYS CONCLUIONS: Tie. They serve different functions and each sound and work a bit better with different content & scenarios. Put on some broadway or classical and you are going to get more emotion and brilliance with HD800S Put on some R&B or synthwave and you are going to get more low frequency enjoyment from HD820 Put on the HD800S in a quiet environment and the sound floats around you. HD820 still good but maybe 20% less "float." Put on the HD820 in a noisy environment and your sound is still good. HD800S still listenable but the music is spoiled at times by obvious background interruptions. HD820 keeps you isolated when HD800S you're at the mercy of your surroundings They are complementary, one is is not better than the other. Both are cool. If you are a fan of HD800 sound sig buying both of these is a smarter decision than a more expensive headphone if you have both times you will be using with and without background noise IMO. You get two very similar, yet different sound profiles that are functionally usable in different scenarios - whereas with a more expensive headphone maybe you will like it when things are silent, but you lose the versatility of isolation. HD820 on its own is a valid option for this scenario as well, but HD800S eeks out more emotion and offers differing soundstage and better fit during those times you don't need the hd820 isolation - making hd800s additionally worthwhile if you have the cash.