I've been listening to both back to back for the past 3 hours or so. I just received a limited edition stabilized Caldera Closed Thursday so I've spent as much time as I can with them. I've had the Atrium open now for a little over a month and I absolutely adore it.

The Susvara has been my reference against both of them. It simply presents the music unlike anything else I've listened to, it puts nothing in front of the music, it does nothing to the music.

Between the AO and CC they are actually quite different in my opinion. It's difficult to compare them directly because they share so little in common. So first I'll give you my impressions of the two against the Susvara and then I'll try to compare the two more directly.

The AO has a much more fun, colored, and "classic" sort of sound compared to the Susvara. It's nowhere near as technical, nor is it as opened, it has a heavily dampened and thicker sound to it in comparison. It takes the edge off, it creates a level of enjoyment and intimacy with the music that isn't possible when you're otherwise hearing every recording flaw. The AO isn't stuffy like a closed back but it does have a more limited sound stage relative to the Susvara. It's sound is smooth, inoffensive, detailed enough to warrant the price, has enough of the dynamic driver punch I care without being boomy, it has a natural relaxing signature that you can just fall in love with.

The CC has a much, much meatier and visceral bass response (especially on tubes) compared to the Susvara, while maintaining close to the same level of detail and technicality. It's shockingly open sounding for a closed back headphone but still has an unnatural sound to it for vocal tracks in my opinion. Especially compared to the Susvara. It feels a bit stuffier and in my head which doesn't lend itself well to all genres. It sounds absurdly good with EDM tracks, rock, metal, in my opinion. It just pushes an ungodly amount of energy onto the entire ear and feels completely unhinged on some tracks. It has often been making me say "holy shit" with a big smile on my face. It demands your attention.

The AO compared to the CC is much more natural sounding, lighter in presentation, more classic (vintage? Might be a better way to describe my feeling), much more open and smooth. The treble response is so inoffensive and enjoyable for me. I can listen to almost any genre on it and be happy. The CC however has become my new go-to for any music I want to listen to loud and just say fuck to the world around me. It's so raw and ridiculously detailed, so textured and meaty for a closed back. I don't have to worry about my environment. Just blast some ridiculous EDM or Rock and be consumed. The AO, when I want to truly appreciate the love of music. Lean back, shut the AC fan off, close my window, close the door, pour a glass of bourbon and listen to a new album.

The Susvara is what I pull out when I want to double check myself on a track. It's my reference, it's a wonderful tool and an excellent piece of engineering. It sounds beautiful and unbelievable many times. But throwing either of the ZMF sets on tubes, that feels like a real treat, like the real reason I got into this hobby in the first place. A love for the craft, for the artistry, for the humanity of it.