Got the Chopin and been listening to it on the Zero/Red cable. It is basically a Zero with a more recessed midrange. The treble is more sibilant than the Zero, although I'd still take the treble of the Chopin over that of something like a Storm or a Z1R; the Truthear bar is just too high.
Overall I am very impressed by the four IEM (Zero, Red, Nova and Chopin). They are all in my opinion correct variations of the Harman target: the more the midrange simulates a proximity effect, the louder the midrange should be relative to bass and treble. The ordering is the same if I sort them by midrange warmth or midrange loudness: Red, Nova, Zero, Chopin. The Nova is a straight-up upgrade over the Red. The other three should come down to personal preference.
My least favorite tuning-wise is the Chopin. The midrange is surprisingly recessed and cold considering that the reviewer who tuned it pretty much only talks about vocals in his reviews. My guess is that he arrived at this tuning from mostly listening to very modern (think post-2015) pop music, where the vocals are already warm and loud in the mix. But out of the four, Chopin is actually the one I'd most likely keep for the long term and do some tip/cable rolling to work around its tuning, simply due to how well built it is. I much prefer resin over acrylic pour, and not having to worry about it when I throw it in my pocket.
Edit: More impressions after a few days of cable and tip rolling, and listening only to my favorite test tracks (mostly Loreena Mckennitt live recordings):
Zero/Red vs Nova: I was wrong about Red vs Nova. The Nova does appear more transparent in the midrange, but at the same time lacks warmth. Actually I'm not really sure warmth is the right word for it. Images of instruments have more "pin-point" accuracy on the Nova, but they are also more dry. The dryness is audible even when compared to the Zero, which has a much brighter tuning. The quieter instruments in the mix (for example, the Uilleann pipes in Loreena's Huron ‘Beltane’ Fire Dance live, in Nights from the Alhambra) are often reduced to their positional cues on the Nova, whereas on the Red/Zero they have more "body". This is the case even though Zero has a much louder pinna gain and treble than the Nova. This may be a BA vs DD issue, idk.
Zero vs Chopin: Chopin is meant to be worn deep, I figured. It is surprisingly comfortable even when worn at the insertion point as my E500. With a deep insertion, the Chopin has thunderous bass, pushing the midrange back even further, for the benefit of reducing the treble. The treble glare is less audible with a deep insertion and a better cable, but is still present especially next to the extremely smooth Truthears. The occasional glare prompts me to lower the volume, which further reduces the midrange. You'd think this much bass can work well for outdoor use, but no. Outdoor IEMs should have extra midbass, not subbass, because no amount of added subbass can compensate for the bone-conducted noise. By the FR, Zero should be a much brighter IEM than the Chopin, but my impression is the opposite. The Zero has as much sibilance as the Chopin, but the same sibilance is much less fatiguing and sharp on the Zero. Chopin also has a dryness issue similar to the Nova, but the midrange is so recessed it is hard to hear. By the time I hear it, it is at a volume where the treble glare is already overwhelming.
Zero/Chopin vs Red/Nova: despite the bass on the Chopin being too loud, I still much prefer it over the bass on the Red/Nova. My preferred volume would be somewhere between the Zero and the Chopin. I think I like bass shelves with a roll off. Between the Nova and the Red, the bass on the Nova is especially underwhelming, likely due to a combination of the lack of roll-off and the midrange dryness.
My verdict: I will probably keep both the Zero and the Red and get rid of Nova and Chopin. Nova to me has more problems than the Red red than it has advantages. Chopin is excellent if you are in for the big bass and don't mind treble glare (I can totally see people perceiving it as detail). Otherwise there really isn't an advantage over the Zero. That Chopin's build and design though, sheesh. Can't wait to see what's next from Binary Acoustics.
