I just wanted to share quick thoughts for the 64audio Nio, used mostly with the O module. Thanks to
@dleblanc343 for letting me try his pair!
Overall, it's a very pleasant IEM, but it depends a lot on what volume you listen to. At low volumes, it sounds a bit too dark and resolution isn't so great. When you raise the volume though, the treble appears and that's when you get the more balanced experience. All my testing was done with the FiR module O, Azla Xelastec eartips and the Lotoo Paw S1 dac/amp (stock cable too, even though you guys probably already know I don't believe in cables). The music I used to test is mostly metal (Dream Theater, Haken, Trivium, Jinjer, Killswitch Engage, Gojira) and progressive rock (Genesis, Porcupine Tree, Pink Floyd). There also was a bit of rock (Chevelle, Soen) in there too.
A/Bing against the Z1R was very interesting to say the least. They both trade blows, but the Nio comes out on top for me. The mids feel a lot more real and full, but the treble is definitely more exciting on the Z1R. While I don't think you're missing detail or resolution in the treble with the Nio, it still sounds a bit further back and smooth. I feel like it blends a little better with the rest of the signature (not v shaped) though, which to me is a very good thing.
I guess the fit is another benefit of the Nio : it's a lot more manageable. I can easily fit the Z1R (deep fit), but you just can never forget it's there since it is so big and heavy. For the Nio, the nozzle is long, so it sits deep while remaining out of the way. Apex technology is another thing : you simply won't get any pressure buildup and you'll be able to wear them for the entire day, no problem.
To conclude this little faceoff, I'd say they're both great IEMs. You're simply trading a bit of treble excitement (Z1R) for thicker, fuller mids (Nio). I'm not sure I would own both at the same time, since they're just not different enough for me to want both.
In my opinion, if there's one IEM that complements the Nio really well, it's the Andromeda 2020. You're getting that awesome layering and that sparkle in the treble, so you're covering the weaknesses of the Nio (the layering isn't bad per se, it's just not a highlight). The BA bass is pretty good for more complicated / complex tracks (mostly for speed and accuracy) as well, so you can pick if you want a more impactful / realistic bass experience (Nio) , or the more reference one (Andro 2020).
All I can say now is that I'm really excited to receive my pair later this month! Worth the pickup if you're looking for a smooth and pleasant listening experience.