It's that, plus Oratory EQs to Harman, which AutoEQ does not, the default AutoEQ target curve you'll find in Peace, Qudelix 5K, etc has substantially less bass than Harman. This is why it kills the bass on basically all IEMs.

https://imgur.com/a/rwHJxPP

>None of these targets have bass boost seen in Harman target responses and therefore a +4dB boost was applied for all over-ear headphones, +6dB for in-ear headphones and no boost for earbuds. Harman targets actually ask for about +6dB for over-ears and +9dB for in-ears but since some headphones cannot achieve this with positive gain limited to +6dB, a smaller boost was selected.

https://github.com/jaakkopasanen/AutoEq/

It's extremely misleading that these curves are labelled as Harman, everyone thinks they are Harman but they are only Harman for the upper mids.

AutoEQ has also historically EQed too high up, and too much high up. This has been addressed in a more recent revision and the precomputed presets now limit themselves to a high shelf above I think 10,000Hz which is a big improvement. Oratory has historically taken a lighter touch in the treble.

Oratory's EQs also tend to be smoother and less extreme, with broader peaks, you can see there is a broad theme but the Oratory curve is smoother.

It's great software and works very well if you use it yourself manually but the precomputed target curves are junk, especially for IEMs. Took me ages to figure out exactly what it was doing. They are getting better, the introduction of low and high shelves is great. But Oratory1990's EQs still better.