Finished testing AP80 with several IEMs:
Tested with Hidizs Seeds, Dawnwood ST08, Hidizs EP-3, KZ ED16.
1. Hidizs Seeds are the best choice without a doubt - they are playing soft, with lots of details throughout the whole range, have good dynamics and linear AFR. But they are the most expensive one as well.
2. Dawnwood ST08 are good as well. Some small signs of HF sibilance and a bit less bass presence. Same in terms of details and overall linearity.
3. Hidizs EP-3 cannot compete with the higher segment. They cost only $25 and it is apparent. More moody, more straightforward, less details, more vocal presence at the front and hiding other distant instruments. Sibilances are more pronounced.
4. KZ ED16. Very bad IEMs for $16 and waste of money - too bright, √-shaped, lots of noise cause of extreme highs presence...
BUT!!!!!!!
MSEB function in AP80 really does some magic: I've managed to make KZ ED16 work so that there is no headache anymore and they are very funny to listen. Instead of √-shape I've got almost perfect V-shape with extraodinary amount of details in lows and highs due to armature drivers. I've dialed Warmth to max (+20), HF sibilance to min (-20) and Air to Soft (-13). Now KZ ED16 can serve its function well and even outperform all other rivals in terms of detail crispness and amount of well controlled lows. Not linear though, would bring much of colorization but usable and very amusing.
Moreover, I've tuned Dawnwood ST08 a bit, adding a bit of bass and bass texture. Now they sound almost as good as Seeds.
Another great function of MSEB settings in AP80 is the ability to save and load your own profiles with names... So, I've created several profiles that can be loaded when certain IEMs are connected.
Still, the best sound for me is no MSEB, no EQ + Audio-Technika ATH-M50
I've spent so long with full-sized monitor headphones...
If my ATH-M50 would be stolen, I would be using AP80 with (in regression) Hidizs Seeds (no MSEB) -> Dawnwood ST08 (little MSEB) -> KZ ED16 (MSEB heavy tuning) -> Hidizs EP-3 (maybe some MSEB).