hey dont mind if I ask how the it03 compares to the the other 3 iems you mentioned.Ive been an owner of the it03 for a while, love it by the way, but have always been curious about the akg n40 and the isine lineup
I will try my best to explain. First I am looking for iem that can drive by my Sony Xperia Z5 because it does not have much power comparing to other smartphones.
it03 is similar to iSine 10 in term of sound stage, but iSine 10, has smoother sound for both mid and high and has no sibilant which is character of planar, but it03 bass does goes deeper and more impact. It is more fun to listen to. iSine 10 sounded more polite than it03. iSine 20 as many people say that it is better than iSine 10 en all departments, I tend to agree especially mid is very rich and sweet which is great for vocal and jazz (in my opinion). I do like it too, but sometimes it's feel like the singer is singing too close to me where as iSine 10 and it03 the singer sing a little far out which I think they give better sound stage. Actually I like all of them, but it30 and iSine 10 give more neutral sound than iSine 20. iSine 20 give more intimate sound than the other two. I might get iSine 20 later on.
I've also tried Campfire Vega, Andromeda they are all good the Andromeda give too good image and separation which to me it seems unreal. I prefer Vega more than Andromeda. They both also easy to drive. Since I will be using iem with my Xperia Z5 therefore it is no use to pay for such high price for them. Vega bass does not go as low as it03.
For Akg N40 it's sound similar to Orivetti with more body and better bass however, it did not try long because my smart phone does not have enough power to drive it.
In conclusion, I like all of them but N40 because it is too difficult for my phone to drive. What makes me decide to get it03 is that I do mostly listen to pop, 60's-90's songs some dance, Jazz so it03 can handle them pretty well and finally when I tried all these iems with
Mission Impossible Rogue Nation soundtrack then it03 is the winner. It gives good sound stage, good instrument separation, and good low bass vibration from tympany which none of the rest can give.
Above is my personal opinion and as I mentioned that they are all good iem and I even think that I might get the iSine 20 later on this year. Due to the more neutral sound and fun sound (quick) it03 is of overall iem for me.
Hope this is somewhat help answer your question exeth.
As I am typing this I listen to my it03 from my notebook through Geek Out iem100