Have a pair of the E10's in my ears right now.
My first foray into the KZ headphones. I have Andromeda's, Tinaudio T2, Meeaudio P1 and a few others
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Build - Feels good to me. The case feels a little rushed compared to my old Sony TWS (just not as high end feeling). They made a weird decision with the case to put the right headphone on the left and left on the right, so it messes with my brain a little when I put them in. Otherwise, the the earphones themselves feel good quality. There are no physical buttons on them (the case has a button for tethering). They did have a weird smell (probably from manufacturing). The earphone cases are made of a resin, which feels nice, but is new to me (my other earphones tend to be plastic or metal).
Audio - They sound great to me. The bass is pronounced a little compared to Andromeda, but I think the soundstage is wider then the Meeaudio P1. If you told me I could get this sort of audio quality out of TWS, I wouldn't believe you. I am playing through samsung audio on my phone, and the music is stuff I have collected over the years (not flac, but good quality MP3).
They are super loud as well, with them being loud enough to block out the office noises at about 70%.
Connection - Seems ok, but I have had 2-3 connection drops on one of the ear pieces (the phone is only a foot away from me) but I am in an office with lots of noise (as in bluetooth, microwave, wifi etc..).
Otherwise they are better then my Sony's by a lot. They drop out all the time unfortunately.
Microphone - Solid. Had a couple of calls already and people said I was clear. The real test is outside, which I will do later.
Battery - Hadn't had a chance yet, but it appears it is inside the little danglely pieces that sit behind your years, because they felt warm after 15-20 mins of use. Not noticeable to my ears, but in my hand I could feel it.
I will continue playing and will update if any show stoppers or major issues.