Some quick thoughts....
Packaging is top notch...professional. The leather carry pouch is nice, but my preference would be a vault similar to Westone W4R. Overall, done nicely! Good assortment of accessories and everything is nicely displayed. Only one cable and I wished it had a cable without a mic.
Build... the shell seems like it is a hard plastic, not sure what type of plastic, I know what I have read. Love the color....doesn't look cheap to me. The nozzles don't necessarily look thin but they still make me question their durability, not sure if it is a question only an observation. I have some long term durability questions overall, but that would remain to be seen. There is a 2 year warranty.
Comfort...I struggle with all IEM's. I have tried the enclosed silicon and some Comply P100 tips, the enclosed Comply's didn't seal for me the P100's are longer and sealed well. I also did receive a good seal from the enclosed silicon, but I haven't tried Westone Star tips yet.. Overall these are one of the more comfortable IEM's I have owned. I won't list all but...Westone UM3X, W4R, SM64,Shure SE 846 are some. There is much talk about the huge memory wires....they are huge but I bent them quickly and found the correct placement for me. I listened for quite a few hours last night and actually slept for 2 hours with them in my ears.
Sound...I was using only the Fiio X5 at 75 volume and no eq. I have not tried the amp yet but I will try it a little later today. I have an E11, I am more of a portable person.
Bass is there...deep, never boomy or rattling. The bass is SO dependent on the seal. I like the bass in these a lot, it appears when it is supposed to and really blends in with the rest of what is going on. It is accurate...I was listening to a FLAC remastered Led Zep 2 ....and in Whole Lotta Love I heard subtle bass booms I did not know existed, even when using my SE 846's.
Mids...WOW they really excel at the full range of mids. They are a bit forward...but it is a sound I like. Compared to my other IEM's it is a clear, vibrant sound. Do not take any of what I say negative they are not in your face and when they are it is meant to be that way. Some of the best mids I have ever heard.
Treble...cymbals have never sounded better. There are times you think OMG here comes sibilance...but it just doesn't happen. The treble is just a well done as the rest of the range.
Notes on overall experience in less than 8 hours of listening...For jazz and blues the Primo 8's are incredible...the tone of the instruments, the clarity and the fact you can hear the separation of the instruments is a wow. For rock I haven't decided how I feel. It appears when there is a lot going on ie..classic rock, hard rock etc...things muddy slightly, I could be wrong about this, because I haven't listened to any one thing for an extended period, just trying many things. One other note based on other things I read...I have the earphones behind my ears with the cable draped over my front shoulder and the mic is hanging exactly where it should others have mentioned it wasn't in front. The sound is very very good overall thus far. Hearing the pick on guitar strings in Dave Matthews and the tone and timbre of instruments.
I need the experiment more with tips and fit and find what I am looking for. I can already tell these IEM's are capable, but I am not where I need to be yet. ACCURATE and CLEAN and liking it at this early point in our relationship.
These are notes and thoughts based solely on less than 8 hours of listening so YMMV.