I bought these for the S12 pro and the kiwi ears quintet. Mind you all of my observations are subjective and being in this hobby for quite a while I now understand how a person perceives sound may be different from one another as there are many variables like ear canal designs that may change how one perceives the sound.
Now after that disclaimer lets see what changes do happen when using the Dunu S&S eartips.
For the S12 pro I observed a slight increase in the note weight across the whole harmonic range. It made the bass more enjoyable and also there is now a touch of warmth to the vocals. Bass also slams harder. There is also a perceived difference in the soundstage as it sounded more wider with the S&S tips than with the stock tips. The treble is also smoothed out a bit. It seems the edginess of the instruments are taken out and it sounds a bit smoother. It also counterssibilance to some extent but don't expect it to magically make a sibilant iem non sibilant, No, it makes the sibilance a bit bearable. Also it provides excellent isolation.
Now for the kiwiears quintet. Things get interesting here. Everything I said above is also true for the quintet except that the soundstage somehow feels more intimate and less wider. Don't get me wrong the quintet still has a huge soundstage but not as large as with other tips (KZ Starline tips). Also the performance in the bass region increase a lot and the bass becomes more punchy detailed and heavy, like now it slams hard. Its still not basshead level hard but its enough to satisfy the bass itch. Treble is smoothed out again and now the fatigue associated with the quintet is reduced a lot. Its still extremely detailed and bright but now a bit smoother. Any hints of sibilance in the quintet is now almost gone. There is a touch of warmth added to the mids and the treble now takes a backseat. The vocals are now more forward in the mix. To be honest it sounds a lot like the hype 2 or the monarch, with the dunu S&S tips. Well not all is well and good. While positioning and imaging is still great on the quintets, the instrument separation takes a hit due to the more smoothed out treble I guess.
In my opinion the Dunu S&S tips are well suited for bright to very bright IEMS or if you have a IEM that you know have a reportedly good bass dynamics but you are unable to hear it then I guess you can try out this tips