Basics
I greatly appreciate the simplicity of the unboxing. You open the box, are immediately presented with IEMs pre-fitted with medium tips, and could be ready to go. I popped them out and directly onto my UTWS3 with little issue (will be mentioned later…) without even bothering with any of the rest of the accessories. I’m not one to tip swap unless the sound signature is particularly displeasing to me (I rolled a bit with the TE Hola), and the white medium tips are good to go for me. Sometimes I have trouble using products with stuff other than what they came with. It upsets me somehow. So it is nice that all the stock options are good enough.

The build quality, cable, and price are definitely the interesting things about this IEM. Without this trifecta, it feels like it would get glossed over pretty easily in the hobby.

First, the IEM: The build is nice and sturdy. No complaints fit-wize. I opted for the painted blue model as I feared the gold would be too gaudy for my tastes. Unfortunately, I had a small hiccup which I noticed when fitting the left side onto my UTWS3: the 2 pin socket is just a little too tight for comfort. It didn’t prevent me from using it with the UTWS3, but I felt the same issue again when I eventually moved over to the stock cable for more listening. It wasn't just that particular combination; the left side has smaller socket holes than the right. If it was just a bit worse I could imagine someone being unable to plug in a cable, or even bend pins/damage something trying to force it together. So be wary of any QC hiccups like this…

The cable it comes with is really beautiful. If I had to nitpick, it's just a few inches too short for my desk setup. As Akros also said in his review, the cable would be just that little bit more stunning if the connector was larger. Otherwise, it's well-behaved, the perfect thickness and braid, comfortable, and has a great chin slider.

What about the price? Well, I got mine for $30 with the Linsoul promotion. I would be surprised if it didn’t regularly sell for about that on the frequent chifi sales. Out of the other budget stuff I have, this is probably what I would recommend/get for myself if it was my only budget pair, even if it's not my preferred tuning (as will be revealed in the music section).

How does it compare to the Truthear Hola? They both graph like warm, dark sets. But to my ears the Hola is a substantially darker replay. I like the stock tips and cable a whole lot on the Hola, but the IEM itself is of pretty poor build quality. The Z300 is just more exciting, better built, with a more attractive cable. Given a choice between the two, I'd pick the Z300 any day, even if it meant paying the extra money.


Music

Yameii Online - Baby My Phone (single) Bass is already mixed to be fairly substantial, but the IEM doesn’t push it over the top, just maybe to the limit of where you’d want it. “Vocals” sound pretty decent here.

Goreshit - The Pain of Relief (track) This has been my favorite sub bass track for a while; the only thing that my earbuds can’t do as well is the crazy vibration you get from this track, and this IEM does it excellently.

Pigeon Pit – Love Letters, Milk Crates (tracks) Not vocal forwards enough; somewhat congested, and I simply prefer more neutral, mid-focused IEMs and earbuds for folk punk.

She/Her/Hers – She/Her/Hers (album) Same issue as with Pigeon Pit really, and in her most recent album the bass is already hearty – it is a bit much with the Z300.

Daoko - Yumemitetano Atashi (track) The mix has some pretty substantial low end, vocals, and highs. The Z300 has tame treble making the highs smooth and inoffensive, the low end is rumbly and impactful as intended, and the void that is the lower mids/midbass in this track means that there’s no bloat influencing the female vocals. In other words, it’s a really good replay with energy everywhere you want it.

YOASOBI – アイドル (single) Really like this song, though I have not seen the anime it’s for. The bass is excellent coming through the Z300, and the female vocals don’t feel recessed at all here.

DR. GABBA - See You, Space Doctor! (track) A big, stinky bass benchmark. Pretty overpowering, and the tuning probably just pushes the bass past the acceptable level to the obnoxious one. Some products I’ve had made it difficult to hear the relatively quiet and distorted vocals in this track; however, this set prevented them pretty clearly.

Roar - I Can't Handle Change (track) Somewhat bloated male vocals and too much energy for the intended vibe of the song.

Jang-Yoon Ju - love song (track) This song has some pretty similar mixing to the Daoko song. Overall an okay replay, if a bit boomy.

My Chemical Romance - I Brought You My Bullets, You Brought Me Your Love (album) Good energy, vocals are slightly masked but not too bad. Really impactful drums in Headfirst for Halos without being too boosted. If this had more treble the guitar might be overbearing but as it stands, it's pretty good -- energetic but not too tiring.

Black Country, New Road - Ants From Up There (album) I prefer stuff with forward vocals on this album. The singer is just too damn quiet. It's not like this IEM plays it back worse than any other non-mid-focused IEM; it just doesn't do it any better, either. The impactful bass can also be a bit much, since the whole album is kind of more of a thoughtful and chill experience. If your goal was an IEM to listen to this album, this would not be the set to buy.

The Marías - Cinema (album) This album has incredibly chill and bassy songs that wouldn't be out of place in the bedroom, at a house party, or blasting out of your car stereo. How does the Blon do with this album? Even though it's already a bassy album, it's a lot of fun with this set. Probably the favorite full album I listened to with this.

yuragi -- nightlife (EP) The stars of this album are definitely night is young and sleeptight. The tame treble of the Z300 means that the distortion never gets sharp enough to hurt you, and the hearty low-end gives the bass guitar the energy it needs.

Kinokoteikoku - eureka (album) Another Japanese shoegaze band. This set actually seems to do this genre quite well, so if you're a fan of the scene, this is probably a set to look out for. The vocals are clear here, there's good impact in the drums, and the guitar is present without being overbearing.

Conclusion
The Blon x HBB Z300 is a sturdy IEM with a great included cable, good-to-go tips, and a metal build for a budget price. The signature is definitely warm, and if you've tried a few sets you'll instantly know whether or not this is for you. It's not going to replace my earbuds since it is inferior in stage and worse for voice calls due to occlusion. As for IEMs, it is overall less fitting to my tastes/opinions on how my library should sound; I still prefer the tuning of the Olina SE. If my Z300's connectors aren't a sign of a larger QC issue, then this is a great pair that stands above the rest of the budget market - provided you're looking for this type of tuning.