I got my S12 Pro about 6 months ago, and after a period of immense buyer's remorse, I finally found the perfect tips that give me perfect resonance and sibilance free listening.
Here's what I discovered along the way:
Final Audio Type E: A slight drop in treble but it caused immense resonance in my ear making sibilance appear in everything, even when pushed as far as it could go into my ear canal.
JVC Spiral Dot: It solved the issue of resonance but sibilance was unbearable. I could swear it boosted the treble.
Fiio vocal tips: It resolved the issue of sibilance for the most part, but sub-bass was severely compromised. A lot of the bass sounded like a rubber band.
Spinfit CP100 Plus: It tamed the treble to a really nice level, but sibilance caused by resonance was an issue.
Stock black tips: Even when pushed far down, resonance was still present and very distracting.
Spinfit CP145: Nice open sound but still destroyed my ears with sibilance.
Truthear Hexa stock white tips: They even make the Hexa sound sibilant. The S12 Pro had no chance.
HiFiMan double flange: Tamed sibilance somewhat but the bass sounded hollow and very, very wrong.
So, what are the best tips?
Well, YMMV, but the stock white tips did the trick for me. It stopped resonance and sibilance. You just gotta insert them deep.
I really wish I could buy more of them somewhere as I'm really scared now that they might get lost or damaged.