Review - HZSound Heart Mirror Pro

Review - TRI i One

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Also available on YouTube in Spanish: Acho Reviews YouTube 

The Tri i One have been sent to me by KeepHifi for me to try out and share my opinions on them. The only request from KeepHifi was that I reviewed them in a short time frame as they are a new launch and there is not much in the way of reviews out there just yet, or at least there weren’t when they sent them to me, I haven’t checked since.

I was happy to accommodate their request, I always am when the request is a fair one and doesn’t become a habit, as long as they are happy with my opinions being honest about what I think about them, which is something that KeepHifi has always respected.

You can find the Tri i One via KeepHifi by visiting this link:

They are also available via the KBEAR official store on Aliexpress:

As always, these are a non-affiliate links, I do not benefit in any way by people clicking or buying via the links.


As I said a moment ago, these are a new launch from Tri and were only released very recently. I promised to review them as quickly as I could and I have had these IEMs a little over 2 weeks, which is basically the minimum I like to spend with a set to be able to review them coherently, 1 week for burn-in and 1 week for listening and testing etc.

The i One are classed as the flagship model of Tri, using a single Carbon PET dynamic driver and coming in at around 250€ at the time of writing this review. This means that they are certainly not a budget set of IEMs but they are still way more economic than “flagship” models from other brands.

I have to say that my experience with them over the last week has been a bit of a roller coaster, going from dislike to like and back again on various occasions, which is one of the main reasons that I like to spend at least 4 or 5 days of continuous use before actually putting together impressions.

Now let’s get on with what those impressions actually are and what my conclusions are regarding the Tri i One.


I have to say that the unboxing of the i One’s was quite an unexpected experience. They arrive in  a large box which is white and simply shows the name and not much more. However, once the box is open, everything turns orange!

The box extends both to the left and the right, with the whole interior being orange, I mean, just look at the photos that speak a thousand words.

Everything is neatly packed and they have really put some care and effort into the presentation of these IEMs. For some reason there is a picture of a deer included that, combined with the orange, sort of reminds me of a hunting store, but I would rather have the deer than some of the anime art that appears with so many other sets.

As far as contents, it is also a very respectable amount. We get the IEMs, the cable, 3 sets of “balanced” silicone tips, 3 sets of “Clarion” silicon tips, a cleaning tool, the user manual, a small net storage bag and a very nice storage case in orange to match the box.

I really can’t complain about the contents as I feel they are more than acceptable for a set of 250€. Ok, they could have included a balanced cable also to really surpass expectations, but I feel that they have covered everything that is needed.

Build and aesthetics…

All of the contents seem to be well made and of good quality but let’s focus as usual on the IEMs and the cable, starting off with the IEMs.

Using Aluminium alloy shells, they opted for a shape that is quite simple but at the same time, uses small curves and deviations to what would have probably been quite boring. The faceplate uses a mirror like insert with the model name and a simple block design, however, the way the mirror finish is done, it changes from light to dark depending on the angle (and makes it rather difficult to photograph, at least for someone like me who isn’t really well versed in photography).

The TRI logo also appears on the forward part of the shells and in general, they do look fairly elegant and I feel they live up to their price as far as aesthetics and build goes.

The cable is a bit on the large size for me personally, as I am someone who prefers thinner cables for IEMs (within reason) but there is no denying that it is a well built cable. According to Tri it is a “OFC shielded pure silver wire”, which is individually wrapped in a cloth type material using a quadruple twist that then splits to two double twists.


Here is where I couldn’t make up my mind with the i One. I did graph these IEMs before listening to them, so let’s start there:

So, straight away we see how far the frequency response of these IEMs is from my preferred target and we can also see a huge peak at 5kHz, my dreaded frequency for peaks. In fact, in the next graph we can see how it compares to two IEMs that I have also tried recently and disliked quite a bit, the Rhombus and the Cencibel (which I believe I haven’t actually published the review for yet, so I guess this counts as a spoiler).

So, let’s just say that I went into this with expectations of suffering that peak. I have to say that upon first listen, that was exactly what I experienced. I was listening to some indy style rock and found that the electric guitars were just piercing in the 5kHz range, along with certain parts of the percussion. This straight away put me in the “I don’t want to spend a week with these” frame of mind.

However, I do know that spending more time with something will sometimes make it grow on me (and sometimes bring me to dislike things that I initially liked), so I persevered and the next day I put on the included grey tips (the Balance tips) and sat down at my desk, hitting play on a jazz playlist while focusing on my work load. After a while I realized that I was enjoying the music and I started paying a bit more attention. I found that some of the brass instruments in the specific tracks I was listening to were actually rather smooth and not coming across as harsh and unpleasant as I expected things like saxophones and trumpets to do.

So, for the next few days, I spent time with the i One and found that they would go from unpleasant to very enjoyable depending totally on my music selection, something that we often forget when talking about IEMs (or headphones), someone's experience will vary wildly depending on the kind of music they listen to.

But anyway, let’s try and give this review some kind of organization and focus on my test list that I always use for final impressions and opinions. It’s been a while since I mentioned it but you can find the full test track list that I use here: Also, each of the tracks mentioned here is a clickable link that will allow you to open the track in the streaming service of your choice.

Starting off with the lowest notes and using my usual test of “Chameleon” for the subbass performance, there is no shortage of rumble in the low end. The performance of these IEMs in the subbass notes is impressive, giving enough of that lowest presence for any subbass lover to be happy without actually being too overpowering. They also do a good job of keeping the subbass clean and defined, even when trying out a track like “Royals” which has a subbass that is not as clean and controlled as it could be, the i One do a good job of presenting it without it taking over the song.

With something like “No Sanctuary Here” or “Sun Is Shining”, which are tracks that focus more on the midbass side of things, the i One does a good job but there can be just a little too much in the lower end of the midbass (the crossover point between subbass and midbass you could say) which can make it feel sometimes like the bass is not quite working together with the rest of the frequencies. This is something that is difficult to explain but think of it like a speaker set up where the crossovers between subs and midrange drivers are not quite set up correctly. This is something that I experience on things like the DT1770 Pro and while it is not terrible, it can just sound a little “off”.

With tracks that use instruments rather than electronic created bass, such as “Bombtrack”, on the heavier side of things, or “Back It Up” which is more of a double bass track, I do feel that there is a little too much presence. This gives a nice round edge to the low end but it does detract from the actual sound of the instruments, or at least the timbre I would expect.

The mids are the point that I most find I changed my mind about. Depending on vocals, some of them can seem a little too recessed. This is mainly in the case of male vocals but I did experience it also with Caro Emerald in “Back It Up” that I just mentioned, or Sade in “No Ordinary Love”, where the voices lose out to the bass playing due to increased midbass and the dip in the mids.

The upper mids are even more of a lottery depending on music though, at least in my opinion. I would find that certain tracks would be extremely exaggerated in those upper mids (with that 5kHz peak stabbing me), such as the upper mids of “Killing in the name of” by RATM or “Light Years Away” by Oliver, whereas other tracks would come across as smooth in those areas such as “Don’t Start Now” by Dua Lipa or "Breezeblocks" by alt-J (a track that can be very aggressive in the upper mids).

Up into the higher regions, I find the extension to be pretty good, giving a nice sensation of openness and air in those ranges. Sibilance is also not bad, with Patricia Barber being just a little hotter than her usual “on the verge” in  “Code Cool”. It is not overly exaggerated as far as sibilance goes, but it certainly doesn’t tame it down either.

Details I feel are a strong point of the i One. They are not the most detailed IEMs I have ever heard but they do portray a lot of the smaller details of music very well, without the need to focus on them to appreciate them, yet not pushing them forcefully towards you either.

Soundstage I also find to be above average, with things seeming to be nicely spread out and well placed across the stage. I never really find IEMs to be overly spacious in this regard (at least in comparison to open back over ear headphones) but I must say I was pleasantly surprised by the i One.

The i One do a decent job of isolation in the upper mid and higher ranges. The lower frequencies do leak through a little more but are still better isolated than the average of the IEMs I have measured so far.


The i One are a set of IEMs that are going to depend very much on the music preferences of the listener. I feel that if someone was to try out these IEMs with just a song or two, they would either love them or hate them (again, depending on the choice of those songs). After trying all kinds of music through them, I have to say that my opinion on them literally changed from track to track (when listening to a random playlist). 

I have tried to relay some of the information while focusing just on my test tracks but I feel that a different review of these could probably be written on a track by track basis.

In the rest of the categories I have no doubts I would recommend them, the build is good, the aesthetics (very personal I know) are good, comfort is good, presentation is good, details are good, performance is good… it’s just the actual tuning and the way it reacts with difference music that will be the polarizing part for people.

I have to say before I finish this review that I have heard a lot (too many?) of IEMs with a very similar tuning to this set recently and the i One are the only ones that I found to be so different depending on music, the others have just been something that I have not enjoyed.

If you can get your ears on a set, I highly recommend you do so, as they might be something that fits you perfectly, or they may not.

All FR measurements of IEMs can be viewed and compared on
All isolation measurements of IEMs can be found on

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