My **** review...
The simple and quick version is these are amazing and you should buy them immediately. I've had what is probably a fairly typical experience with chi-fi. First I was blown away that I had so many options with multiple drivers and detachable cables and all kinds of things that seemed like they should be far more expensive. Having only experienced IEMs from Klipsch/Monster/other well known but generally low quality for the price Best Buy fare, chi-fi sounded amazing. Then with so many options, most being a flavor of the week/month shortly after their release followed by critical reviews coming in after that, I started to become disappointed. The **** seemed similarly flavor of the monthish but I figured the piezo tweeter was something I hadn't tried before so I might as well give it a shot. I'm happy to say these live up to the hype and more!
First, their comfort is very good as long as I wear them over ear. Worn down as designed they cut into my inner ear but over the ear solves this problem. The stock cable is a little short for this purpose and is rather prone to tangle, so I'm using the cable from the Tin Audio T3. As for the sound, bass, mids, and highs are all excellent but for me the highlight is the bass, specifically the subbass. Everything else in this price range I've tried has boosted midbass and rolled off subbass. Not the case here as the subbass digs deep and hits with authority but not overly bloated. Speed is very good as well and I've found myself listening to rock with my favorite bass players to enjoy the goodness. Primus has never sounded so great! Moving on to the mids, they are equally impressive and have taught me I don't like the V signature as much as I thought I did. They are extremely smooth and have excellent separation with metal that so easily turns into a bloated mess. Finally moving on to the highs, they're in my opinion the weakest part, but still far above average. The piezo tweeter has an interesting timbre that almost makes it sound like I'm listening to a record. It's a bit odd but not necessarily a bad thing as I could see these being a bit overly analytical and boring without that odd bit of timbre. Detail is very good across the board but I do find the lower treble slightly recessed, making some songs sound slightly on the dark side. I find no issues with sibilance unless it's a badly mastered recording or a recording that's victim to the loudness wars. The treble extends nicely to add a decent amount of air. It's a very refined, subtle air that helps things sound nice and open. Others have described the sound stage and making you feel like you're in the front row and that describes things perfectly. They sound imtimate but open and not congested in the least. The first song I heard that I didn't know that started with instruments in the right ear and a whispering voice in the left almost made me jump out of my chair because I thought someone had walked up behind me and started whispering at me.
As for negatives, they are few and minor, especially considering the price. Bass rolls off below about 40 hz so EDM and things like that are missing a little bit of impact. I can also see the treble being a bit polarizing since the timbre isn't completely natural. I've found that I really like the timbre but not everyone will agree. Depending on the music you like, you may also find them a bit too revealing. Poorly mastered recordings sound like poorly mastered recordings and the **** is very revealing of any odd artifacts that other less revealing IEMs can mask. I like to listen to a bit of an audio book to evaluate mids and that quickly reveals coloration in the mids. With the ****, I noticed a lot of static in the background that I first attributed to the tweeter doing something funky. Switched to the ZSA briefly, listened closely, and heard the faintest hint of that static that was just masked due to the ZSA being far less detailed and the mids being recessed.
All in all I couldn't be happier with this $20 purchase and I'd really love to see what someone could do with these drivers by spending some extra time tuning them. Refine these even further, charge 100 bucks for them, and I think you'd have a top of the line killer.