At least Hifiman actually rebrand the headphones and call them V1, V2, V3/Stealth, Organic. You do know what you're actually getting with Hifiman, you know if it's an Arya V2 or an Arya Stealth or an Arya Organic. Unlike for example Audeze where they don't tell you and aren't even consistent batch to batch.
Besides this though, they just aren't that different.
Oratory has profiles for the Arya and Arya Stealth, but I used the OG Arya EQ before he did the Stealth one, they are very similar. In Oratory's measurements the Stealth is just generally smoother. For that matter I used his Arya EQ on the Edition XS before he measured that and it sounded good.
Crinacle's measurements also show very small variation:
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In general with Hifiman, Oratory's EQs sound right from the get go. Even if they are not from the exact same headphone!
By contrast, my experience with the LCD-X 2021, even applying Oratory's EQ directly, it was definitely off, and I had to tweak it quite a bit to get it sounding right. Audeze don't even have batch-to-batch consistency. I don't have a measuring rig for over-ears, but I do for IEMs, this is my Euclid vs Precog's (he uses the same coupler as me and our measurements generally match). Oratory's measurements are different from either. No way could I have EQed this off other people's measurements.
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Hifiman by contrast is bang on and very consistent. I mean look at this, these are
five totally different headphones and they are more consistent than Audeze is between two different instances of the exact same headphone.
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I don't think it's a problem that they make small incremental improvements to their headphones, when they clearly label the revisions, and usually also drop the price while they're at it.