KZ AZ09 Bluetooth 5.4 Module Wireless Waterproof Ear Hook Extra Long Battery Life Bluetooth Cable for ​KZ ZST/ZSTX/ZS10/AS06/AS10/BA10/ZSR/ES4 (B pin)

I'll give you a quick TLDR: They are good, buy them. They have latency on HD audio which sucks for watching video, but if you turn of HD audio they still sound great and the latency goes away. The rest of this is specifics about the the audio. Honestly, these sound amazing and I don't really feel the lack of lossless audio. The AAC audio is very high definition and it doesn't really sound different than one of my bluetooth DACs with lossless paired with the same iems. It seems that the digital amplification circuitry is very good a similar to a proper dac. No "hiss" at low audio levels and no crunchy fade in's from silence to audio. Reading some of the other reviews people have mentioned that the pairing audio is super loud. I would agree with that, but in my case I never ran into disconnections so I never deal with it. I think if you also experience solid connectivity that shouldn't be a problem, but your success will vary. I will say that I am really please with how stable the connection is as a huge guy. This is going to sound dumb, but I'm used to headphones cutting out if they don't have really good bluetooth because bluetooth signal has a hard time transmitting through flesh. Being 6'5 and 350lbs, I'd say 1 out of 4 bluetooth headphones I use cut out randomly at times because of this issue. These didn't have that issue with either headphone. One tip I will give people with these is that, if you are dealing with serious latency while using them to watch things like youtube, it seems like these headphones are slow on the decoding of the HD Audio. They sound genuinely fine even without HD audio on, so if you are using them with Youtube a lot you might turn off HD audio. Oh, and the case is 10/10. Seriously, I have a case for my IEM's and it's fairly compact, but given the nature of the IEM's I use the most, they are just chonky. It's hard to make anything that isn't thick that can safely store them. This has just enough room and the rounded edges makes it about comfortable as a case for these IEM's can be. It makes me want to 3d print a similar case, but with a little extra room for a cable.

Another great purchase to write about! I work around our property every weekend and being a music lover I always have ear buds in so I can listen to tunes while I work. The problem is apparently my ears are misshapen in some way that makes every ear bud I've tried not seat correctly so the buds fall out of my ear. Anyone who constantly has to readjust or push their earbuds in can feel me on that point. I wanted a quality ear bud that fit securely and wouldn't come loose as I worked - and this product didn't disappoint. I will say that being Chinese made, it has some funny quirks - it sounds like the lady announcing that the device has connected says "Connectate" instead of "Connected". I don't really care about that though - all I care is that the sound is good quality and the buds stay firmly in my ear. This product did both very well and I'm loving not having to take my buds out and reseat them every 5 mins. I'm using a after product foam type ear piece - you can squish it down tight, put it in your ear, and it will expand to fit perfectly. Battery life has been great for the time I've had these (about 6 months). I'll work around our 7 acre property for 6-7 hours without having to charge and it still has juice left if I forget to charge them. This also has an option to be used as a corded ear bud as well, which I did find useful since I travel a lot and use headphones with a plug while flying to watch movies or listen to music. Now I have the best of both worlds. From a cost/value perspective you can't beat the price and they do seem to be of good quality. I would recommend this to anyone looking for a versatile set of music buds, that stay put in your ear and block out unwanted noise, keep their charge for 7+ hours, and are easy to pair to your phone/tablet or computer. I'd definitely buy them again.

Update: I decided to replace the unit. This replacement is working great and I am enjoying using my KZ Z10 Pro with the bluetooth. While walking at the park I noticed the sound dropping on the left ear for a split second, and again the next day it happened again. So far it's very infrequent and doesn't bother me, not what caused it but at those times I was in motion with my phone in my pocket. Battery life has been good, i haven't ran them to low yet, the longest I used them in one use was like 2hrs. The call quality could be better, sounded a little choppy for what I was hearing and I'm not sure how I sounded on the other end. Comfort wise, it felt good, it's not heavy on the ears and it conforms well. When I use my IEMs at work, the dangling wire tends to bother me a bit with the pull in my ear hooks but with these units, it just sits comfortably on my ears. Overall I'm satisfied using my IEMs for more than just work now. I don't plan on using this Bluetooth for calls as much as I do for music and it does well the Z10 pros sound like they are wired. Original review: My left ear hook unit seems to not charge, I lift it out of the case, it turns on and then turns off by the time I securely place it over my ear. Its looks like it's charging when I place it in so i am not sure what's happening. The right unit is working fine and sounds great but I haven't even had a chance to use both together except for the initial setup and one other time after. I've tried resetting them and resyncing, making sure it charged over night, and placing it correctly without moving the charging case. Nothing seems to work and the left unit just turns on and off. One star for comfort because I only worn a single unit.

removing 1 star. I cannot turn off the flashing bluetooth lights, which wake my wife up in bed at night. so i'm removing one star down to 3 stars, since i'm now limited to using them only during daytime. this goes back to needing an app to control things like voice, permanent set equalizer, and LED. I had a pair of panasonic earbuds, that i really didn't like oveall due to fit (constantly falling out of ears) and flat sound, but at least i could turn off the dang LEDs. I'm using this with KZ ZSN Pro Dual Drivers 1BA 1DD in Ear Earphones. They paired easily and quickly with my phone so yipee. I do wish they had a dedicated app for permanent equalizer adjustments similar to fiio (but my fiios broke after 3 days so they're out). the "turn on" "turn off" "disconnected" "connected" "performance mode" voice over lhas a hilariously bad stereotypical asian accent, and it is crazy loud. i try to keep my headphones off my head until after i've turned them on, or take them off before i turn them off because the voiceover is sooo loud. unfortunatly there isn't any warning before you get blasted with the "low power" voice -over. so that one hurts. They have a sleek 3 fast click performance mode feature that helps the earbuds sound better. i'm not sure if this simply uses more juice to power the drivers tighter or if it changes volume and equalizer settings, but it does have a nice effect on the quality of the buds i'm using with this set. The wrap around cord is comfortable for me, and stays in place very well. i've done gardening and other active things, and haven't felt them slipping off at all, and haven't had any fit induced discomfort. I intended to use them bicycling with a helmet but haven't yet, so cannot comment. I would like a bit more control on the device, and here is where i bring the review back from 5 to only 4 stars. only 1 button per ear, the buttons control on/off (long press) pause/start (1 click) ....3 clicks gives you performance mode. 2 clicks left/right ear gives you advance or rewind to next/previous song. no volume controls, that needs to happen from the source, like your phone. I LOVED this feature on my fiios, with the ear dials, fantastic, but not here. there isn't an app for volume or equalizer control at least not one that i could download. i saw some sites elude to the existence of an app, and i even tried to download one from a link i was hopeful for but it just sat there, and i worry that i just downloaded some malware. (nothing bad noticed yet, but maybe it's just monitoring things for a while....intrusive thoughts i know). with better controls and a MUCH quieter voice over (even with the bad accent) i'd give this 5 stars.

I bought these as a test to see if I would like the style and fit before dropping $80 or more on a good pair. Connection is awesome, regular earbuds don't connect for me from the interference in my environment, these are a solid connection that hasn't failed or dropped out once. They are more comfortable that I would have thought. The battery life is great, like in excess of 8 hours for me. The volume could be a little more as they seem underpowered sometimes. There have been a couple of times that I wished I could turn them up a little more but they were already all the way up. With BASN iem's the sound is fine with no buzzing or hissing in the background. For my purposes I can't justify buying a more expensive pair just for the louder volume. It wasn't like it wasn't loud enough to hear, just wanted a bit more. After more than a dozen pairs of wireless earbuds($30~$120) that wouldn't keep a connection more than 5 seconds without dropping signal these are the best listening experience I've had. Way better than expected.

I’ve been using the KZ AZ09 adapters with my Melody IEMs for about five months now, and they’ve quickly become my go-to setup for work and daily use. The bass hits hard, the clarity is excellent, and they get plenty loud without distortion. No compromises in sound quality compared to wired use—they drive my IEMs effortlessly. Pairing is instant, and I’ve had zero connection drops. I’ll leave my phone in my truck and walk around a job site or warehouse, still connected clearly over 100 yards away. Battery life is phenomenal—I get multiple full workdays without needing a recharge. The charging case is simple and solid. It announces when you’re connected, and it’s never let me down. The touch controls are responsive and cover all the basics: play, pause, skip, volume. I’ve made calls with them too, and the mic quality is surprisingly crisp—no one’s ever complained. They’re also ridiculously comfortable and secure. I forget I’m wearing them most days, even after hours of moving around. The build quality is legit—they’re sturdy, not flimsy, and they’ve survived multiple drops without a hiccup. At this price, the AZ09s are a no-brainer. If you’ve got a favorite pair of IEMs and want to go wireless without losing sound quality or reliability, these are absolutely worth their weight in gold. ⸻ ✅ Pros: • Fantastic bass and clarity • Incredible Bluetooth range (100+ yards) • Long battery life (multi-day use) • Reliable, quick pairing • Comfortable and secure all-day wear • Durable build—survives drops ❌ Cons: • None that I’ve encountered

for it's price, it's pretty bad, pretty much everyone reports online how the right ear-piece just stops charging about a month after owning them, my issue is constant crackling and broken audio, I've only brought them as back-ups when my other wireless pair wasn't charged, rarely touched them except to test them at home and they are broken, Bluetooth 5.4 is also kinda old for 2026, can't test if it's waterproof because it pretty much is broken before it could get wet and the controls can be confusing as it doesn't really give feedback on what mode you toggled, just *beep* and you have to assume you did something right, also 48000 Hz 16 bit DVD peasant-quality audio is degrading to my ears, it reminds me of my childhood of when I have no money for myself to spend and my parents wouldn't hook me up with awesome hardware, so I never knew what was "good and cool" and just had to work with what I had. as a general rule of thumb for buying audio gear, get a DAC and wired headphones for PC, for phones get the matching brand (I.E Galaxy Buds for Samsung Galaxy, Airpods for iPhone), and if you want wireless for PC, make sure it's made to be a high quality bluetooth headset itself or even better, a USB connected dongle if you want to know why I bought this over-priced, mass-produced product, is because I was shopping for IEMs and thought it would be awesome to have a "hybrid" of being able to conveniently swap between wired and wireless, the IEMS are still good wired, and let's me listen to 24-bit 96000 Hz audio, but this purchase never sat right with me, especially considering how my JBL 710BT mogs these, and JBL isn't even impressive I just bought them long time ago and use them for comfort when I can't sit in a chair for 8 hours, but I'd rather just have my IEMs at this point to be wired only because the type-C pins are slowly chipping and when the protective layer fully cracks and falls off the pins, the pins will start breaking, so heed my warning shopper! or feel the wrath of buyers' remorse!

Works perfectly. It's comfy and has a good grip on my ear, no chance of it falling out. Battery lasts a long time. Charging case is nice too. My only problem with it is the flashing light when pairing is a bit too bright. I was worried about choppy/poor audio, but it turns out it was a problem with my computer's bluetooth usb dongle. It works fine when paired to my phone.

Have turned my IEMs into amazing earphones. They connect well. Make sure that they've been disconnected from every other Bluetooth. A minor niggle is that they have very short range. Otherwise they're fantastic

Bom

Just what I was looking for, Quality seems good, as is the sound,

Overall a good product, but the one thing bugging me is when I have the volume low and on AAC codec which is the highest quality on android it will cut out quieter frequencies. Otherwise, it works well with my KZ ZSN PRO X's with huge range, sound quality that sounds the same as wired except for the issue I mentioned which happens below half volume.