Hey there, my friend!
I have not compared them before.
Let's do it from a FiiO F9 perspective then
FiiO F9 vs Oriveti New Primacy - Starting with the bottom end, F9 has a similar bottom end, with a very good extension but ONP has slightly more definition, the midrange is less forward on F9, where it is somewhat forward on ONP, and the treble is rather smooth and relaxed on ONP, while it is energetic and maybe just a bit peaky on F9. Even though its price is about 1/3 of ONP, FiiO F9 proves to be an excellent performer, providing, at times, even more details in the high registers and in the upper midrange. Where ONP excels is in the bass, where it feels more rounded and snappier, and although its treble is very smooth, it also features a pretty good extension. Both IEMs are excellent performers at their price point, but their signatures are different ONP appealing to people looking for a smooth and relaxing experience, while F9 appeals more to folks who are looking for an uplifting listen
I hope this helps!