Audio Technica ATH-IM04 SonicPro Balanced In-Ear Monitor Headphones


Headphoneus Supremus
Pros: Gobs of detail - easily outranking the (aged) Westone W4. Fairly flat FR with good treble representation.
Cons: Not much sub-bass impact. Fit was awesome for me and I have small ears, but I can see potential issues.
There's a lot of different companies trying to earn your ~$400-500 in exchange for a shot at upper-middle class audio bliss. Audio Technica did a pretty good job here. There's not really anything I can fault aside from the level of detail and sub-bass not really comparing to my FLC8S, though doing quite a bit better than an older four-driver IEM, the Westone W4. It's a perfectly respectable way to sink your teeth into multiple drivers, even if not a guarantee to be the best you'll ever hear.
Pros: Sound Stage, Range, Clarity
Cons: Isolation and Fit



Firstly, like to thank Audio-Technica for the ATH-IM04 loaner for this review. This is my first listen to any Audio-Technica IEM’s so was excited to hear what they have to offer.
The ATH-IM04 comes in your standard retail packaging, and proudly displays the Japan Made logo. What you get inside the box is surprising simple for an IEM that cost $599USD $699AUD. The IEM comes with three pairs of silicon tips (S,M,L) and one pair of Comply foam tips, as well as your carry case, which is a leather clam shell with a zipper and that is all. I was a little surprised with the lack of accessories for a flagship. Most companies tend to put the most stuff they can fit. I would love to have seen more options with tips, as I did struggle to fit one perfectly, and ear wax cleaner is also a norm with IEM’s these days. They also have a removable cable which is a nice option.

The IEM themselves are built solidly, and are on the larger size for an IEM. Having quad balance armatures, this was no surprise, but companies like Shure and Westone have managed to get their BA’s into smaller housings. Regarding the size of the housings, the nozzle that holds the tips is rather short compared to the size of the IEM, which makes it harder to fit properly inside your ear canal. Having a limit number of tips, finding the perfect fit might be a struggle for some. I found that isolation also became an issue, as well as noise bleeding from the IEM themselves. I think a little modification and extra tips will make this a non-issue.
Having played around to get the best fit I could, I was onto the listening. First thing that hits you when you hear these is the clarity and definition of sound coming from the IEM. Instruments are clear and clean with great separation. Sound stage is outstanding as well.
The sound signature of ATH-IM04 is warm and mid focused, but with strong bass and nicely extended treble – warm, smooth, full bodied yet still good in soundstage is a great description. Bass reaches down to 15Hz easily, but deep sub-bass isn’t very obvious due to the equally strong mid-bass region that gives more body. Treble extends all the way up and offers good sparkle and crispiness, mainly as a supporting role in the whole presentation rather than standing out as an element on its own. It can however sound a little metallic when the volume is turned too high.
There is that no sibilance issues at all, and it isn’t plagued by over-brightness but actually sounds rather smooth.

Using the ATH-IM04 as a musicians IEM was great. Playing drums on the Roland TD-30KV showed great detailing in the IEM. Low end bass from the kick came through nicely and the cymbals was nicely separated. My only issue was again the fit and isolation, moving around did mess with isolation.
Having a beautiful sounding IEM can only go so far, you need it to fit properly and comfortably, especially when you are paying hundreds of dollars. The sound from the ATH-IM04 is beautiful and clean. I think they take the clarity mantel from Heir Audio, but the fitting issues does distract from the overall experience.
Type: Quad Balanced Armature Driver
Frequency:Response 15 – 20,000 Hz
Maximum Input Power 3 mW
Sensitivity 101 dB/mW
Impedance 14 ohms
Weight 8 g
Cable Detachable 1.2 m, Y-type
Connector 3.5 mm (1/8″) gold-plated stereo mini-plug, L-type
Accessories Included Case, silicone earpieces (S/M/L), Comply™ foam earpieces (M)


Member of the Trade: Portable Modder
Pros: Sound stage, depth of field, smooth BA signature, can upgrade cable for different sound sig
Cons: Nozzles are too short and need some modification to fit better. Bulky


The IM-04 is quiet bulky, but it is rounded off in the inner side, and with the short nozzles I have found no fitting issues whatsoever.  The body is shinny with pitch black color, and a gold logo of Audio Technica.  The shells are made of hard plastic, and of what kind of quality and durability is up to guesses, but I will have to go with "Japan made" and say that the quality and durability is more than just good.  The plastic catches minor scratches easily.  I would advise to not drag it a long any hard surfaces (any surfaces) at all....even if between themselves 
.  IM-04 comes with detachable cables (one of the main purchase point from me.)  I can switch the stock 3.5 cable to other cables with microphone, balanced, 1/4 can imagine the uses of it.
Fitting:  Memories wires.  I found the best way to wear the memories wires is by stretching it out, having the right bud (L to the left, R to the right) on the side.  Using one finger and hold the ear bud in so that it doesn't move or fall out, then use another hand and slowly wrapping that stretched memories wires around your ears.  ***Becareful*** while molding and wrapping the wires around your ears, please do not be so rough on it, the cords and the plugs are made by plastic.....and that means you can easily crack them, or damage them by the use of "man handling, or strong armed"
            It just dropped right in, and that I only needed to do my "tip rolling" for the best seal and fit.  After around 20 minutes, I have found myself having to press the buds inside my ears were falling out slowly. Then I found a head-fier fellow to suggest the adapter to extend the tips out a little.  I did just that, and has stopped falling out slowly.

*****Notice***** Being Balanced Armature units driven, the IM-04 is picky with tips and seals.  It really really need a good seal and tight fit to perform at it's best.  The stock silicone is sweet, the comply or foam tips will attenuate some of the sound performed.  Best is to be used with Silicone tips, and while pressing it, hooking it in, make sure that you feel the pressure built up in your canals.  Using silicone tips may be annoying if you are jogging or walking, the hollow air inside and the tight silicone walls hugging your ears canals wall = the best footstep microphonic......I said "footstep microphonic" because you can totally hear your steps, and....heartbeat.  Use Sony Hybrid tips for a better isolation and this microphonic filtered out some what.
Comfort-ability:  Very comfortable, I can hook it in, and enjoy music for hours and kind of forgot about wearing it.  The con is that I can not lay in bed with it and sleep with it....I have other pairs for this, and if you are curious ? FX-750 is for organic, warmer, relaxing music to sleep.....or TTPOD T2 for detailed, smallest volume of enjoyment to sleep.
I will be pairing this IM-04 with my Sony Walkman NW-ZX2 and listen to different genres of music with CD quality FLAC 16/44.1 and High-res of 24/96, no MP3 (lossy)
Sound : The sound is very smooth, musical, and a bit darker (warmer) than many would have expected.  Especially if you have jumped from it little brothers, the IM-01-02-03.  You would think that it is a different kind of creature 
.  I will cover this later.

**Noted** the warmth here I am talking about is the warmth if compared to Balanced armature nature only. It is not a generally warmth IEMS , but more like a detailed, relax, musical, and will expose the artist intentions very, very well.

Lows, if you ever thought that BA units will typically have faster, tighter, and not as tonality accurate when expressing drums hits, impacts and powers....well, prepare to be wrong.  The lows in IM04 is very dynamic.  It has the "boom" of the Dynamic drivers, and the "fast respond" of the BA units.  It will dive down...deep down, and will show no struggles.  It responds so fast and in some tracks, you may be able to find the subtle and transitional missing beats in some tracks compare to your favorite Dynamic IEMS (in my case, it is the FX750).  An example here would be if there is a "Ppahh Wwhhaacckk" you hear with IM04, with Dynamic driver I would hear "PhhhppWhaack"
The bass beats is so authentic, and the excellent uses of Two BA units dedicated to the "Low Spectrum" alone.  You will be able to enjoy different genres universally and equally very very well.  I am very surprised at the level of organic timbres and quality bass beats from classical and midi genres, and then playing some Dance, electrics genres, it can become fast responding + boomy together.  I think the "bass lover" will love this pair, and not necessarily "bass head."  If you love musical, warmer, fast, accurate, articulated, dive deep, and flying to the sky while keeping the bass body, texture, and vividly showing you the emotions of the lows spectrum, you will be addicted to the IM-04 lows and warm signature.  I found the tonality very natural and organic.
Mids, with the powerful and warmer lows, the mids are nowhere being veiled, the extensions, the air, the layer of each instruments are beautifully blended together in the mids spectrum.  The excellent extensions and the air allow the instruments to show itself more vivid and detailed.  Vocal is presented very well, neither too forward nor too far, just enough to allow you to pay attention to it, and have all of the instruments submerge you into the wide, vivid, accurate placement of the instruments
Highs, while having powerful lows with beautiful quality and mids spectrum not being affected by it, the highs spectrum is somewhat affected.  The highs spectrum appear to be warmer, the highs textures is smooth, sexy, lushy, but will not satisfy people who love highs spectrum, or music genres that mostly call upon highs, such as rocks, or metals.  It is a bit boring in away of not enough metallic tones, and too smooth of body textures.  But I know there will be people who appreciate this kind of highs as it will allow you to just enjoy music, and be relaxed.  I found it to be excellent with Ballad, Midi, Dance, Trances.  Now, don't mistake my expression here about the highs.  The highs here is just not bright enough for Rocks, and Metals addicts, but it is neither rolled off or lack of details or extension, or is most people it should be just detailed, Sweet and lushy 
I do think the warmer highs and the powerful lows are what giving the pair the aspect of a musical, relaxing kind of sound signature.
Soundstage:  IM04 forte....Excellent !  The depth of field is represented beautifully when pair with ZX2 walkman, instruments placement is excellent.  The width is in the "large" scale....kind of like enjoying a live performance in a stadium when compare to my FX750.  The 750 appears to be "concert hall" in size.  Again, that 3rd dimension "Depth" is excellent.
Now here is the Bonus
Remember the first initial reason why I made the purchase toward IM-04 ? Detachable cable
I upgraded my cable to utilize NW-ZX2 TRRS plug (an additional Ground, and not circuitry balanced)  Sony stated that it improves the sound quality.....X_X this is where I am it the cable ? the TRRS with additional ground ? or both, but the upgraded sound quality is definitely there.
The cable I purchased was TRRS 3.5mm and 7N-OCC as in 99.99998% of Copper, and OCC = Ohno Continuous Casting (Ohno = the inventor name.)  I know it is confusing :wink:
The bass has become tighter, even faster....more articulate and no longer boomy, but very similar to IM03 lows.  The vocal became much more forward, the mids become brighter, highs becomes much brighter.  Remember where I said highs lover and or Rock/Metal genres addict will not too excited by IM-04 ? yeah ? Well they would be jumping up and down here as highs has become so annalytical and bright, very similar to IM03.  The amazing thing here that dropped my jaw, and almost made me yell "Audio Technica ! What the hell ?"  Yes, the bright signature, but not harsh, more metallic, but no sibilant, unless intended......seriously! What the hell ? Yes, it is that good.

Remember the sound stage being so wide ? and the depth was presented amazingly ? Yeah, it is more pronounced here, more vivid, more depth.  Probably by cleaning up that boomy bass a bit and tightened it down more
Conclusion, for IM04 to be totally transformed from a warmer, more relax, with lushy highs to turn into more articulated bass and annalytical highs with the touch of metallic tones here is a wonderful experience by itself.  The awesome thing is that while being brighter with the uses of BA units, there are no sibilant 
 Rock away !!!!!  Two different sound signatures (Stock form = musical, soulful, lushy vocal, warmer and relaxing VS upgraded quality cable for bighter, cleaner, clearer, more annalytical kind of like the IM03) by simply switching the cables.  The IM-04 is worthy of being the Flagship IEMS in the IM series from Audio Technica.  I love it ATH!!
*****As always***** please make sure that you tested the pair out before you make your decisive decision to purchase it.  My taste, ears, sources are different than your.  I hope you enjoyed the review, and that I have helped.
Thank you for reading
Great review, bro!
great review! i wonder why the im0xxx series have seemingly short nozzles whereas the imX0 (im50, 70s) have these bean pole length nozzles! why the two extremes (id like somewhere in between, thank you very much!)
have you get the chance to compare them with 846 or ie800? are they a good match for EU cap zx2?