My previous setting on WM1Z: WM1Z, v2, alt dac, CEV (for neutral and better sub-bass rumble)
I have been exploring warm signature, because I just realized that I like warmth and I rarely explored this region. So I aim for warm but still maintain the high resolution. I am at this setting now: Warm, v2, alt dac, gain=0, U region. Still testing it with some IEM, what I get is warm analog like the original firmware with J region but with a good resolution and still maintaining the sparkle without any sibilance. Timbre is still right, vocals are right for both female and male, Madonna is still Madonna (no transformation to Big Momma, Michael Jackson does not sound like Nat King Cole as well), in "Welcome To New York" by Taylor Swift, no sibilance detected, it does not sound digital as well. In "Alive and Kicking" by Mr Big, the drum slam at the end of the song is impactful (good to excellent, not yet incredible, I want more air slammed to me). IER-M9 sounds fuller, Xelento does not lose its sparkle, XBA-Z5 sounds distant on some song but probably because my ears needs adjustment to its sound as I rarely listen using it.
The logic behind it, is because I feel that ESS chip is more suited to combine with tube amplifier, so the clinical U region adds the needed presence that warm signature needs and also give the sub-bass rumble as well.
Prior to this, I explored neutral with J3, which reminded me with SP 1000 M but with better imaging and soundstage