You should grab the ZES if you like U signature, after quite easy mod, they are more open and the bass is the best KZ bass i ever heard, beating the long time champion budget bass for me, the XUN driver. Impactful but tight, good texture and reach deep.
To be honest I grab the ZES more than The Hola as beater set. They have Z1R DNA, if H40 is like baby Z1R, then the ZES is like his little brother of the baby, but have better bass part (H40 wins on technicalities of course, they are 1DD + 3 BA) but as overall, I like ZES more than H40. Super value fun set!
Take off the nozzle filter (its a thick paper damper), puncture a hole with needle in the center, and put back the nozzle filter.
This will give much better airflow for the bass, tighten the mid bass smear, much cleaner bass and mids area (this will bring mids a little bit forwarder).
Secondly, if you want, take off the outer aluminium shell so left the green plastic shell, there are lot of vents on plastic shell, thus lead to larger soundstage because of semi open, but with trade off of passive isolation and ghetto look. A bit hard to open since you have to have force to "peel" the aluminium shell.
Edit : picture added
I like the MST implementation of ZEX, having one generic ZEX (Lafitear LM1 MST+DD) incoming. LM1 has been reported an IF scenario that if ZEX was left in uncivilized forest but sounding wild and good.
And that LM1 is the only one MST implementation that has non-dual magnetic/cavity DD, with less bass impact to enjoy the MST. That ZES mod sounds like a LM1 tuning, I may grab one when I find a good deal for ZES for fun.
The recent KZ ZNA and ESX certainly re-impressed me about how well KZ is progressing their IEM manufacturing. Both are ”hit”, not ”miss”.
History of MST implementation
1st try: CCA NRA and ZEX
Less dampened MST with DD
NRA had some agressive peaks which was the very first gen “listen MST can produce treble extension” type tuning.
ZEX came later, it had some minor patch on peaks of MST, the fun tuned yet nicely balanced MST+DD implementation.
ZEX Pro (CRN),Crin attempted to fit ZEX to his target curve, a challenging effort to tame MST. KZ added one BA (maybe generating negative phasing to cancel out MST’s peaks), it was less dampened final output from upper mid to UHF, a lot dampening took place for taming KZ’s dynamic DD by filters.
End result was terrible. ZEX Pro timbre took hit , FR fit to somewhat Aria/HOLA style, but tonality felt you are listening to badly implemented noise cancelling headphones with muffled mid and lower range. This is like you are listening music in a very high milk-colored fog, disturbing imaging ever took focus.
This Finished the MST implementation attempt by KZ. We see no further newer releases from them after that. Until the ZES, KZ is still willing👀
ZEX , ZEX Pro, and ZES you can see some back and forth in tuning
ZEX and DQ6S, I can see ZES is DQ6S family, KZ tried to fit. That’s pinna gain compensation tuning (U12t, N5005) grand tuning family.
However! There is tribe of Mountain Gorillas out there sourced same ODM devices of KZ playing in wilderness. Lafitear.
A shady shady company which offered “Beryllium-coated DLC“ LF1 for $15. That Berry-coated DLC thought to be an artifact of imagination , until Thieaudio Elixir/KiiBoom Allure‘s introduction after that LF1.
LF1 is probably a false advertisement, as you see most of Lafitear product sounds funny from their description. “see through” is misinterpreted as “sea thread” 😄
Then Lafitear jammed MST with DD on LF3 Plus (MST+DD, discontinued) and LF3 Pro (MST+BA+DD, a misinterpretation of ZEX Pro, BA wasn’t used to offset MST Peak but actually adding further peaks on top of MST👀, all uncontrolled wilderness of driver), a wild MST appearance.
Later they retuned LF3 Plus to LM1, the one I mentioned. A bit calmer Orangutan LM1 seemed to be.🦧
According to Lafitwar, MST‘s natural tuning is per that yellow FR
By supplementing lower bottom and mid by medium sized DD, I‘m interested how LM1 would sound.