I got my Nio’s yesterday, and put in about 4 hours of listening.
Off the bat, I was a bit worried I wouldn’t like these based on measurements and overall first reports on its smoother treble, but after some brain adjustment and just pure musical enjoyment, I can say without a doubt that these are fantastic iem’s. My favorite from 64 Audio tonally actually.
Bass is definitely at the forefront, and boosted significantly compared to neutral with m15 and m20 modules, whereas with MX it nearly sounds like a different iem, which caught me off guard. MX really makes it sound like a monitor, and very similar to U12T but with better bass texture and timbre, but less airy and extended higher registers.
My favorite iem is the KSE1500, and I wanted a complimentary sound to it, and this fits the bill perfectly. So perfect that it’ll probably get most ear time going forward.
I can safely say it outshines these iem’s I’ve owned (solaris, IER-M9, Andro S), and personally beats some of the best universals I’ve tried (U12T, VX and Z1R) for its versatility. The treble is what I’d consider its “weakness” as there is shelving, but the resolution and detail is not sacrificed, it’s just not in your face.
Honestly, I am quite easily fatigued by energetic but etched treble in iem’s, and Nio makes for a very very enjoyable listen, with tons of character, and just a slight compromise in tuning (not a traditional hi-fi tuning, like what Sony did with Z1R), but for the better. Of all the iem’s mentioned, it sounds like a mix of U12t and Z1R, with less raw treble resolve, bass more similar to z1r with m15/20, otherwise very reminiscent of U12T with MX, but with superior bass. The flexibility of tuning is pretty sweet. I need to get the Fir MO now, as it seems to bridge the gap between MX/ M15, and sounds like my near ideal.