EarAcoustic Audio STA-Hi End Universal IEM
Redcarmoose Labs April 4th, 2025
EarAcoustic Audio was established in 2015 in Shenzhen, China. Though for most intents and purposes they are best known for TFZ around here. And while I did demo a few of The Fragrant Zither IEMs in shops back in 2018, I ended up purchasing other IEMs above their price point. Still it needs to be addressed how TFZ has had a long history here at Head-Fi and been many listeners gateway to China built IEMs. Though what is hilarious here is there is no listing of the name TFZ in marketing promo material for the Angel Series, like they are trying to distance themselves from the name. During the last few years I have been sent two really special IEMs called SuperTFZ, which of course just like this current reincarnation, is ultimately TFZ. For better or worse it is hard to sluff-off a name you have made for yourself, be it an attribute or a deficit. To better understand EarAcoustic we can look at their output as confusing, or genius. Why? Well typically a brand may choose 3 in a debut series to introduce a line of IEMs………but never 12 different IEMs. You can only imagine the full-on wing, the EarAcoustic wing of the merchant storefront, if the vendor chooses to carry the whole line of products. And that’s just the thing……..with so many made and how they actually are very different in both tune and driver make-up……..you feel at risk of missing THE ONE if you don’t carry all for sale as a vendor. While I’ve been told the complete series is coming my way, it really starts to get confusing. Like your first ideas of the ultimate top-of-the-line SPA-Hi End Limited Editions would be the same only with finishing differences. Oh noooo….that’s way too easy for the brand. Each of the Limited Edition, Max or Ultra have different sensitivities and impedance ratings. The 6 gram SPA-Pro, 14 gram SPA-Pro Ultra and lighter aluminum SPA-Pro MAX each have a different shell material construction. The regular SPA-Pro and STA-Hi End is 3D printed resin, the SPA-Pro Ultra is Zinc Alloy CNC, and the SPA-Pro MAX is CNC Aluminum. Then the STA Hi-Pro has a $39.90 retail price to Hi-End Max edition at $89.90 with not one 10mm DLC DD, but an addition of a separate 6mm Polymer DD. Such creativity and selection means that they have all bases covered. Not only that but there could be different uses and jobs to do. That upon closer inspection as example the SPA-Hi End MAX goes for extra vocal energy where the cheaper STA-Pro MAX has lesser vocal intensity yet still balances the bass with extra high-up treble energy over the SPA-Hi End Max.
All these choices may just keep the prospective IEM buyer contained into making a choice or two inside of the EarAcoustic Audio brand area. Here especially we find glamour in sparkle-faceplates and Universal Custom shell design. These ear-shape specifics are from the compiled ear-shape database compiling 1000s of ear-shapes to make a form pretty much guaranteed to fit your ear. Such a shape allows for the IEM module to fit closer and adding ease of use.
Unit disclaimer:
It has come to my attention that the STA-Hi End and SPA-Pro share much the same tone, with the SPA-Pro having slightly less treble and upper midrange. Thus much of this review is identical to the STA-Hi End review.
Top: SPA-Pro
Bottom: STA-Hi End
Left to right: Spa Hi-End Ultra, STA-Hi End and STA-Pro
Comparison SPA Hi-End Ultra
189.90 https://penonaudio.com/Earacoustic-SPA-Hi-End-UItra
Look, these two are not even in the same ball-park. Sure the EarAcoustic Audio build aesthetics makes an attempt at making the two look the same. I mean they have gone far out of their way to make the SPA-Hi-End-UItra and SPA-Pro look the same. But with a different driver methodology, the SPA-Hi-End-Ultra has solid Zinc Alloy shells and a 11.4mm DD. That is not to mention the total Ultra weight at 14 grams in comparison to the 6 gram weight of the SPA-Pro! Part of this occurs from the SPA-Pro build which is chrome plated resin. But beyond that the SPA-Hi-End-UItra puts out a thicker sound, a denser note-weight and meatier sound. Even a bigger stage and a more 3D top to bottom, side to side and front to back sound! Though upon first hearing the comparison it is probably the extra grunt of the lows that puts the pants on the SPA-Pro. A more real idea of note-weight generating a more real idea of music. Do I advise saving your money and just buying the $189.90 SPA-Hi-End-UItra? Yes and no, meaning the SPA-Pro still has a different enough sound that both could actually be complementary in a collection. Still if I was to leave and go to a deserted island and had a choice of only one, it would of course be the SPA-Hi-End-UItra! There is a product of deep and warm character that makes the SPA-Hi-End-UItra just that much more of a memorable experience in the end, one that I want and need to be friends with.
Today I’m starting out at the STA-Pro. This particular IEM costs $39.90 is a 10mm Ultra Clear Analysis DD and 6mm Composite DD.
EarAcoustic STA Pro 10MM Ultra Clear Analysis Dual Magnetic Composite Diaphragm+6MM Composite Diaphragm Dynamic Driver Hybrid 2Pin 0.78mm In-ear Earphone
Specification
Unit: 10MM Ultra Clear Analysis Dual Magnetic Composite Diaphragm+6MM Composite Diaphragm Dynamic Coil
Sensitivity: 108dB
Impedance: 22 ohm
Frequency response range: 10-30kHz
Wire specification: 0. 78MM dual pin oxygen free copper and silver-plated wire mixed weave 1.2M
Quality in Sound:
Now one of the main points I want to get across in this review is the fact that the art of making IEMs is progressing, and the under $40.00 realm may just be where the greatest leaps of progress has been? My point is this STA-Pro is audiophile quality. If you have glanced at any of my reviews I never write Quality in Sound as a header……..but I am here. Probably I really need to emphasize that this is not the expected bass heavy consumer tune, it is the very opposite here. Yep, we are rewarded with a tight low-end, remarkable pace and a well itemized stage displacement. OTB the STA-Pro sounded almost gritty. Really this euphoric smoothness is after 6 days of burn-in. That somehow I just knew burn-in would be a huge deal here, and it was. This added cohesiveness was met with a more fluid greeting of a bigger stage holding ample individual sound characters and poise. I mean sure I judge IEMs by price, sure everyone does even if they don’t realize it. As yes, you can note that the shells are chrome plated resin, and not actual CNC like some of the series here. Only the opposite is going on here. I’m looking at the two bottom vents and the single top vent and wondering where this enlarged stage is? That while this is in no way a vocal centric tune, the bass is so well positioned and that while the bass does not have full-on 3D carved sculpturing, it is still detailed in the most careful and polite of ways. There is this flowing of sonic additions, and a nonchalant way, and effortless and natural way about the STA-Pro….far beyond the price point offered, or guessed here.
I mean I could picture a person going through IEMs in a shop and finally arriving at the STA-Pro and stopping what they are doing, only because this is both warm and smooth, yet holding just enough detail and an accessible airy sound that just won’t stop. People might wonder why I score the STA-Pro so high…………it is just this surprise when listening, the completeness and the honesty of tone here, that sure it’s two DDs so off-timbre is not an issue. But the fluid airiness, the effortlessness, that this kind of tune could get set-up to be on the wrong side of analytical, but instead they traveled into warmth and this slight warm tinge is just right, never going muddy and never getting at a loss of note-weight either!
STA Series:
STA-Pro:
STA-Pro Ultra:
STA-Pro MAX:
STA-Hi End:
STA-Hi End MAX:
SPA Series:
SPA-Pro:
SPA-Pro Ultra:
SPA-Pro MAX:
SPA-Hi End :
SPA-Hi End Ultra:
SPA-Hi End MAX:
SPA-Limited Edition:
SPA & STA Style Explanation:
1. SPA series compared to STA series overall style has a slightly richer, more intense atmosphere.
2. PRO series more professional, more pure tone and higher reduction.
3. The Hi-End suffix has a stronger sense of atmosphere and higher hearing tolerance.
4. Ultra and MAX represent the need for higher thrust combination, more rich sound.
SPA & STA Process Explanation:
SPA-Hi End / SPA-Pro: 3D Resin Printing + Precision Spraying
SPA-Hi End Ultra / SPA-Pro Ultra: Zinc Alloy Plating + CNC Post Treatment
SPA-Hi EndMax / SPA-ProMax: 5-axis CNC process for aeronautical grade aluminum
SPA series products are standard 0.78MM double pin LITZ coaxial cluster oxygen-free copper + silver-plated wire combination replaceable line.
STA series of products are standard with 0.78MM double pin oxygen-free copper + silver-plated wire combination replaceable line.
Cable rolls:
Top down:
A) Included 0.78MM dual pin oxygen free copper and silver-plated wire mixed weave 1.20M cable. (Free)
B) SPACE modular cable: 4 shares, single share is 133 cores, a total of 532 cores of silver plated Oxygen Free Copper. ($99.90)
C) Penon OCC849 Single Crystal Copper HiFi Audiophile IEMs Cable Type-4 Litz configuration, 6N single crystal copper cable. 8 strands, single strand is 49 cores, a total of 8 × 49. ($99.90)
Included cable:
A) I have to say the included cable is nice here. Just easy to work with and gets us 90% of the possible sound. Maybe I just like thicker cables, except also the additives of the extra size 3.5mm plug, the metal chin-cinch and separator…….all and all this in no way looks like a cable that comes with an under $40.00 IEM? There was also a very even tone that joined to the STA-Pro, held a great stage and separation. Truly if someone was contemplating never using 4.4mm, there is a guarantee you would stay with this cable on, even if you had many other 3.5mm choices.
Penon SPACE:
B) As a 4.4mm update here, it is easy to tell by going over to the 3.5mm modular SPACE cable plug that the 4.4mm amplifier is doing part of the magic. As such a different set of capacitors and amplifier layout help enlarge our stage. The bringing forward and in separation of STA-Pro imaging is the money here, showing us there are new and better places to live, with our IEM in place. The thing is that because the SPACE cable never colors the sound, we have basically the same as the included cable tonally, only the added material has gifted us a more moving musical experience, simply letting the STA-Pro tone exist bigger. Here is the thing, we really don’t want any changes made as far as I’m concerned here. I mean maybe a slight thickening, but maybe not………and that is how on the fence I am about changing the tonality here. What we have is great pace and filled with flourishing images. That while I call this slightly thin, this thinness is really on the best side of clarity, and partially due to the mid centric Sony WM1A character. One way I test this is to then go over to the ifi GO bar, one of the more expensive Dongles and play a song I know well with the SPACE cable and MacBook Air. The beautiful thing here is sure the GO bar is on the darker and more detailed side of Dongle personalities, only with the STA-Hi End we are still pushing that clarity, plus rigid and not so rigid imaging out to the sides, along with what I would call audiophile clarity. Yep, this STA-Pro is definitely not a murky consumer bass tuned IEM, if it was it would lean that way with the ifi GO bar set-up. That the STA-Pro walks that line of musical and absolutely detailed, way more detailed than the price would lead you to believe.
Penon OCC849:
C) Back with the Sony WM1A in 4.4mm. Well the OCC849 has been a cable of considerable merit lately. This is simply because of the increase in stage and deepness obtained by bass for starters. Really, really I’m asking myself here. Really? I say that as I thought the STA-Pro may border on too bright. This is simply due to the known midrange energy projection of the OCC849. But no, none of those issues here. Why? Because the OCC849 is also equipped with an alloy midrange personality that can with certain IEMs add a smoothness to any midrange brightness, and that’s what we have. Only the STA-Pro went and ran with the OCC849 tone to make it the very best today in our uses. Now we see more mountains in the distance, now we see farther into the sky…………But, there is one final major gift here that is taking place. The lows……….heh. The lows are now fully defined, creating a more even, complete and balanced STA-Pro experience. In fact if you were to buy one cable for the STA-Pro, the OCC849 is the ticket. Sure the OCC849 is over 2X the money than the original STA-Pro, only $39.90 IEMs are not what the $39.90 IEMs used to be. So we need to view them as more expensive products worthy of a cable of this caliber. Look I could go on and on about the OCC849, only this is an IEM review. So let me just conclude this section with a stance that you will fully understand OK? Remember how I was describing the STA-Pro as having just a slight floaty quality? Well the deal here is that we are now cleaning a little of that up, having it become replaced with clearer more believable realities here. That I thought I would not benefit from the OCC, only I did in the end, bring a smoother and slightly darker treble and midrange and adding heft to the bass…………..really all we could ever need or ask for at the $90.90 price bracket. Don’t believe me, well try the OCC849 and see if what I’m saying will be true for you too, I don’t see how it wouldn’t be?
Music tests:
As far as choices go I have chosen two songs that are almost opposite here, in that the Metal song showcases guitar timbre and female vocals, and the second World Music song showcases male vocals and bass, for starters. After finding these two songs I realized that I don’t need 5 or 7 more song demos to get my STA-Pro points across.
Music set-up:
Sony WM1A DAP, MrWalkman’s firmware, the Penon OCC849 cable and PAC LStips.
Delain
Apocalipse & Chill
Chemical Redemption
44.1kHz - 24bit
Timestamps only pertain to digital file, not video.
Probably the best thing to do in the middle of a (trying to be objective) review is to take two days between listening. And that is what I did. I used both songs on one day, then got up the next day to continue. The other thing that I did was listen to two other IEMs between that time. If chosen right by happenstance the effort will allow for a better objective take on the IEM in test. Besides getting the ideas from the first day to choose these songs, I heard both character ideas and technical ideas which seemed to be well explained by the music, hence put also into words here. Those IEMs between testing were kind of an ear-reset, being one IEM had way, way more bass and the other IEM was a 5BA lesser bass, more treble intense IEM, yet balanced nonetheless. What I’m getting at is the STA-Pro has a bewildering way of tricking you with the feeling that you have all the bass you need, for starters. Only through trying a bass heavy IEM in testing do you realize that there is more bass to be had in the iEM universe. Same as adding the all 5 BA IEM into ear-comparison. Now truly coming from the 2 (10mm and 6mm) STA-Pro sizes of DDs, then having these BGVP DM6 Universal IEM 5 BAs offer the role of a faster, and a critically edge laden production which goes miles to promote a different view of the music.
Above BGVP 5BA DM6
That as always there is no perfect IEM, only close to perfect listening experiences. That each build methodology finally holds true into driver character due to the actual style of driver…….as DDs have their tone and character, BAs have a different one, Planar IEMs hold even different attributes and drawbacks..............depending on what you are looking for. And for the most part these driver character ideas never change totally even in regards to tuning. Sure there are always new supposedly better driver make-ups……….and it is true that as a whole there are less DD (different sized) mixtures. That as a reviewer we are fully guilty of romancing a new style of tone. Simply just like hearing new music that is enchanting the first time, driver ideas can offer thrilling ways to hear old songs. Yet when it comes down to it we are still (as reviewers) still judging performance in relation to applied and accepted ideas in relation to price for realism, or fun. That as always, balance and poise create an enjoyable experience. Really the factors of evenness, completeness and correctness are the goals here, yet also at times some IEMs are more those things with one style of music to another. So well roundedness is important, sometimes, it just depends if an IEM is really really good at only a few musical genres, and who cares if it doesn’t do everything!
So as far as songs go there are many ways to record, and producers even follow genre templates. Meaning each musical genre can have a recording style that a few recording technicians follow. With the female fronted Dutch Symphonic Metal band Delain a style of brighter guitars is noted. I’m not going to list them here, but rest assured the mixing and tonality of such bright guitars is found often in the Female Symphonic Metal Community, though this track has exceptionally bright guitar tracks. Maybe this is to compete with the Female vocals? Yet what we are concerned with is the tone, that while there are actually many levels of correct and many levels of off-tone. That while the guitar tone is forward and bright it is not nasal or synthetic, as much as it actually is suppose to be, if that makes any sense?
And you see that is the exact place I like to say that the STA-Pro is the real money here. And the one-two-punch is the vocals of Charlotte Wessels taking placement into the stage. Not only taking placement except taking perfect vocal positioning. It is times like this that reviewers shake their heads and come to the realization that price is only a number, this ability is real and of value here. You see it is not just the test if the STA-Pro can do this tone or not, but how technical and balanced it is to do this tone and other tones to boot!
At 00:24 Charlotte Wessels vocals come to play and all is just right, that means not too forward or too back……just right. But more than that these are performing like a vocal IEM. Meaning we can hear her (probably overdubbed) take-in breath at the end of 00:23. What I’m trying to say is these perform vocal details well beyond the asking price. This is just the waters we swim across as 2025 is in full-force! And of course the timbre is going to be correct as DD, silly! Look I could go on and on about the drums and the bass……..the 01:11 accents to the beat are clear as day………and way more correctly done than you could guess from looking at the price. But I will say this, nothing is perfect and while there is adequate note-weight, the drums are slightly dry sounding, and it is not really an issue as they are fast and fun, but not as deep and round if you want to know the truth.
Timestamps only pertain to digital file, not video.
DCD
Anastasis
All In Good Time
44.1kHz - 24bit
Ok, now that last statement about the thinner drums may actually be from the recording then accented by the STA-Pro, I’m too lazy to check with another IEM, plus I don’t want to switch IEMs at this point in the review. As such it doesn’t really matter at the end-of-the-day. Because at 00:00 we are greeted by a style of bass here. And really this section is about the trick the STA-Pro does. That fact that the bass is not really the lowest of lows, that somehow it doesn’t need to be to still install the feeling that it is all here. This broadsided me yesterday when I was writing this review and I got a message to test the Penon Vocal cable with the ISN H20 IEM. Yep, there was bass to be found, more sub-bass action shaking stuff-up………….going deeper and more profound. Now that doesn't make the STA-Pro wrong or anything, no……..just a different way of doing things. Does this mean the STA-Pro is bad for EDM? Absolutely not, in-fact I went over to some EDM and again that is the riddle here, that the bass is fast, clean and complete, so much so that it makes the rhythm move the EDM track along just like it’s not even trying. Though remember the OCC849 is in-place seemingly adding the extra lows over the included stock cable or the same price Penon SPACE. The OCC849 is the very best cable I tried with the STA-Pro.
So what about the male vocals?
I’m glad you asked! First off, I know why Penon sent these over here. They are exactly my tune, in that I truly love the style of tune. Wait, I don't even want to go back to the song here in question………ADD off to an EDM track and I can’t stop listening to it……..yep it is that good.
OK finally back to the song in question!
That is the thing leading up the the vocals in “All In Good Time” there is a presence, and a display of elements, except really they are bathed in less definition, really a lot of the imaging here is that way, as talked about prior. It is not bad, just different maybe the 10mm and the 6mm competing for sonic space in the overall mix, I don’t know? But this low-end is hearty and satisfying none-the-less. At 00:29 Brendan Perry makes his entrance…….and of course there is a blend here. The perfect blend has to do with all the ample reverb in this song. I mean as far as songs go, this song is a study in the extra use of reverb. Only at 01:47 we come to realize that the magic here is that we are getting both up-front and clear vocals, with the perfect fall-off of reverb tails in the end. Also such effects tend to make the stage the very biggest ever, I will swear the stage was never this big before......not this big?
What? The personable feeling of the vocals, I mean I know why Penon sent me this, it is really really good. Around the 01:50 mark the bass beat doubles up to become a full-on rhythm in timing. Now sure I have heard this more finitely sculptured, and yes the bass is in a careful place, but I like the effects here. At 02:23 Brendan Perry adds emphasis coming right after a long spell of Dark Wave synths. That if anything, the very personal vocals tend to be replayed with the exact correct positioning and overall demeanor, where you would not guess to have them any other way?
Build:
At the end of the chrome plated resin shell Is an aluminum ear-nozzle. The three air-ports allow for two vents to flow out the back and one a top the faceplate. The size, shape and weight are just right. At 6 grams each we are not heavy or too light weight. A solid metal Zinc Alloy faceplate, yet the back-half is resin. Such 3D universal custom backs have a shark-fin for closer fitment. That sound isolation is not great, and less than average, maybe the resin, or all the vents here? The overall nozzle shape allows for all kinds of ear-tips. And……the flush 2Pin holes make cable changes easy and fun. The more I look at the STA-Pro…………..it goes with this copper OCC cable I’m trying. And the thing is, when an IEM starts to sound really, really good, that affects its looks too!
Package:
Conclusion:
Wow. So the level of what you get for under $40.00 has had the bar raised. Sure I was suspicious of a chrome plated resin design. Then I started to fall in love with the drivers and their abilities………and the rest…….history. There are so many levels of win here. That sure, all the different models are confusing, and really I am happy that I only received one EarAcoustic Audio IEM at the start. And while $39.90 is still a lot of money, it is probably more important for the buyer who spends $39.90 to get a well tuned and well designed IEM in the end. I say this as there is a chance that the buyer of the EarAcoustic STA-Pro may make only one or two purchases this year. So that increases my responsibility to inform and to be complete in a review. That the EarAcoustic STA-Pro is amazingly well rounded and could in-fact be the only IEM you own. That it somehow replays all music genres and does it with flair. That flair is both a slight excitement combined with correct timbre……that in the end qualifies the EarAcoustic STA-Pro as a style of deserted island IEM. This completeness means you won’t get tired or bored with playback. This idea of sound is not perfect, yet does every aspect of every musical genre I tried. As maybe luck would have it, the EarAcoustic STA-Pro goes with many sources yet scales proportionately with your best gear. This sonic success is most likely designed-in with no luck only TFZ experience?
Cell Phone use:
Common really? With the included cable and powered by just my humble Samsung cell phone the EarAcoustic STA-Pro is crazy good, probably the best this year from a phone. You see with the included cable we are getting 3.5mm authority, and a deep-big bass response that is not cloudy or even going toward murkiness? That while complete, it is only maybe missing a deeper clearer noise floor obtained from an audiophile DAP? The stage and imaging is absolutely amazing from a phone and will be many folks' end-use scenarios!
Look…….as always I have been as complete and up-front as I know how with this review. And just by chance I feel the STA-Pro will be many peoples full-on hit purchase of the year. Why, it’s simply well-rounded and goes with any source you have on hand. Simply due to sounding both correct and interesting. Remember this is 2025, the past year this budget realm has seen total improvement, now we are finding another single step forward in sound.
$39.90
https://penonaudio.com/Earacoustic-STA-Pro
Disclaimer:
I want to thank Penon Audio for the love and for the EarAcoustic STA-Pro review sample.
Disclaimer:
These are one person's ideas and concepts, your results may vary.
Equipment Used:
Sony WM1A Walkman DAP MrWalkman Firmware 4.4mm and 3.5mm
Sony WM1Z Walkman DAP MrWalkman Firmware 4.4mm and 3.5mm
Sony TA-ZH1ES DAC/AMP Firmware 1.03
Electra Glide Audio Reference Glide-Reference Standard "Fatboy" Power Cord
Sony Walkman Cradle BCR-NWH10
AudioQuest Carbon USB
Samsung Phone 3.5mm output
ifi GO bar Dongle 4.4mm and 3.5mm
Well I really find a value here, where TFZ has not tried the get the most treble details going but instead worked with smoother, yet nice midrange detail and 2X driver abilities to bring it. The strange part is the Zinc Alloy 11.4mm DD Ultra weights more (I’m guessing the most of the series) at 14 grams. The Ultra weighing more than the IEM priced above it....... that is an Aluminum construction? Still I have a long and intimate relationship with the Ultra, you could say it is my preferred style, regardless of weight. Meaning I don’t care what it weighs!
Yes 12 different IEMs! A lot to take in!