Custom IEM Review: Hidition NT-6 Pro – Clear & Precise Fun
Hidition, located in Korea, re-launched their business and product line near the end of 2011 and I was privileged to be able to review the NT-6, which is one of their two flagship products. The NT-6 was designed with a reference sound and has 6 balanced armature drivers in a 4-way configuration, delivering a ER4 like sound with greater detail, resolution, clarity, and capability. The performance level is very high in comparison with what I have heard and left a lasting positive impression on me.
Since the NT-6 is one of two flagships, with the NT-6 pro being the other, I was asked countless times about how the NT-6 compared to the NT-6 pro, so I talked with Hidition about the differences between the NT-6 and NT-6 pro, and we decided it would be a good idea to have a full review of the NT-6 pro. When the NT-6 pro arrived I have to say I was shocked by the sound, and not in a good way. Over 200 hours of burn in tamed the offensive treble, making it only somewhat offensive, but it still seemed too bright and analytical. I did have some minor fit issues, and when I contacted Hidition with the sound and fit issues they agreed to remake the NT-6 pro as well as my NT-6 since it had the same fit.
They both came back with silicone canals, a much better fit, and the sound of the NT-6 pro was already significantly better out of the box. The sound was less offensive and much more musical as well as more spacious and I was informed that a different coupler was used due to my (and another person’s) feedback. The artwork is beautiful and the shells are amazing and on par with some of the best I have. There is a language barrier when talking with Hidition; however, even with the language barrier, Seoung ByoungHa has been great to work with and I wanted to give him a huge thank you for the opportunity to review the NT-6 pro and for all his assistance in getting things right. Click here to see all my custom IEM reviews and information on custom IEMs.
More pictures to come.
How to Order, Warranty, Options
The Hidition NT-6 pro cost 1,232,000 won plus VAT in Korea and $1250 internationally. You can change the language from Korean to English at the bottom left of each page, although not every page translates. International ordering is done through the www.hidition.co.kr website, selecting your items, then selecting buy.
Options: Selected on the product page. There are some awesome artwork options, which you can see at the gallery, although they look better in person than in the images.
International shipping: $30; $40 for shipping with insurance
Warranty: 1 year parts/labor; 30 days for fit
Design and Fit & Finish
The NT-6 pro is a 6 balanced armature, 5-way system with 3 sound tubes in an acrylic shell with silicone over acrylic canals as an option, which my unit has. The cable is detachable and uses a slightly protruding socket mount for the cable. The canal portion of the shell is backfilled with acrylic, encasing 3 of the drivers.
The fit and finish is very good and one of the better finishes I have seen, including artwork that is very well done. With a clear shell, it is hard to see where the silicone on the canal stops and the acrylic starts, but you can feel it. The shells stick out further than many other CIEMs such as the JH16, IERM, and 8.A, but on par with others such as the 5-way and i9pro. Since I also have the NT-6, which has been redone with silicone canals and stunning pearl artwork, the fit and finish on that is also very good except the canals aren’t as smooth as with the NT-6 pro, although I can’t recall if it was that way from the start or because I used an ear lubricant on the canal.
The NT-6 pro includes a unique metal carrying case that is compact, a cleaning tool, a soft wipe cloth, instructions, and a frequency response chart in a nice box. The case, while larger than the original, still isn’t the biggest so care needs to be taken to close the case all the way since my shells are rather large.
I was sent both the standard and upgrade cable. The standard cable is much better than the upgrade cable due to microphonics issues with the upgrade cable. However, I still prefer the upgrade cable because with the upgrade cable the midrange is more in line with the rest of the presentation and the overall presentation is a bit brighter, but smoother and more refined overall, with a more 3D space. All listening for this review was done with the upgrade cable.
Standard cable on the left, upgrade cable on the right
Hidition is coming out with a new upgrade cable that looks and feels like the standard cable but sounds like the upgrade cable. I can’t wait!
With the silicone canals and canal fill, the NT-6 pro isolates better than a standard hollow shelled acrylic CIEM. While not as good as a silicone shell or solid acrylic, it is close to the latter. 7.5/10
Disclaimer: My review is a comparative review, and since I have many similarly priced custom IEMs, my perspective is based on equal competition. My goal is not to tell you how great the product under review is, but to explain the sound signature and characteristics as well as bring you a balanced account of the strengths and weaknesses to help you decide if this particular custom IEM is for you. This critical look at the product will almost always result in both strengths and weaknesses being revealed. It is my firm belief that you should buy a product based on the sound you prefer, or the sound for your particular purpose. If you don’t know what you want, read through the reviews and try to imagine if you would like the described aspects of the sound.
The NT-6 pro received 100+ hours of burn in as is customary before I do my serious listening. The following custom IEMs were used for comparison: Hidition NT-6, Heir Audio 8.A, JH Audio JH16, Rooth LS8, Spiral Ear SE 5-way Reference, ACS T1 Live!, Ultimate Ears In-Ear Reference Monitor (IERM), Starkey SA-43, and Earsonics EM4.
Upon first listen the NT-6 pro sounded great, although it is very likely that the drivers with 200+ hours of burn in were used for the rebuild. My initial thoughts, when listening to the NT-6 pro in comparison with the NT-6 was the additional depth to the presentation and a clearer and brighter sound, but with a musical presentation. The bass also seemed to be more enhanced than my initial unit. The initial unit had a very hot top end, but it settled down after 200+ hours, but still wasn’t as musical as the replacement, which makes sense because Hidition did make some changes to the sound.
Bass: The bass of the NT-6 pro is not typical, but impressive. What I mean by that is the enhancement is in the deep bass region and the mid-bass is very lean and neutral, reminiscent of the NT-6 and ER4. The perception of enhancement is dependent on the track as many bass light acoustic songs sound close to the NT-6 while pop, electronic, etc. songs are definitely enhanced. While there isn’t too much warmth, the bass is still full and involving due to the enhancement down low. Compared with the NT-6, the bass is more prominent and fuller but in comparison with something more bass heavy like the 8.A, the NT-6 pro sounds relatively thin even though the NT-6 pro has a bit more deep bass capability. Speaking of capability, the deep bass can really rumble and shake, giving a tactile feel and “sense” of power while still retaining excellent control. While the 5-way has more rumble and better dynamic range, the NT-6 pro isn’t too far off and the NT-6 pro gives a better sense of control. Detail levels and texturing are excellent, surpassing the JH16, mainly due to a clearer focus of the presentation. As should be expected from the sound signature, the NT-6 pro is fast enough to keep up with any track, rivaling and even besting the JH16 bass speed. While both the JH16 and NT-6 pro have enhanced bass, there is a different feel to each due to the JH16 having more warmth and bass enhancement.
The bass extends all the way down with full impact and rumble, which is in its own right impressive. If you listen to acoustic music, you will probably realize that, while the NT-6 pro isn’t on the warm side, it is still exciting as it enhances the lower tones of bass notes, giving a slight accentuation. Turn on some electronic or pop with deep bass and you will feel the full effect of the enhanced bass, adding flavor to the music. You won’t be able to mistake it for neutral (that is what the NT-6 is for), but the quality is simply amazing.
Midrange: The original NT-6 pro I received had a recessed midrange which was remedied to a large extent by the premium cable. Hidition now uses a premium grade cable with the stock cable ergonomics and microphonics so you get the best of both worlds.
The new NT-6 pro has a better balance across the frequency spectrum and the midrange isn’t recessed. There still is a laid back feel to the midrange because of the bass and treble enhancements, but vocals and midrange instruments sound right where they should be. The midrange is clear and precise with speed, articulation of note and voice, and very high resolution. The presentation is very spacious and has exceptional depth of soundstage with great instrument placement. While the midrange is very good and articulate, it doesn’t have the organic sound of something like the 5-way or T1 Live!, which give strings more body and have an overall thicker presentation. The midrange of the NT-6 pro gives you immediacy of detail and a precise, analytical sound with top notch clarity while still having musicality.
Treble: The NT-6 pro is the brightest CIEM I have, no doubt, but the quality of that treble is excellent. The boost is not peaky as with many others such as the JH16 and LS8, but more of a boost above 8K, at least in my ears. Sibilance isn’t an issue unless it is an issue in the recording, and even then it is very forgiving of sibilance in the track due to the frequency response. Due to the boost, the treble isn’t at a level that I could even mistake for natural, but it is very listenable since the quality is quite good and passed all my treble test tracks. While the decay isn’t quite as good as the 5-way or even the NT-6, it does have better than average note decay for treble instruments, and is forgiving of poorly mastered treble.
Covering my favorite aspect of the NT-6 pro first, the soundstage reproduction is amazing. The space is very large, just a hair smaller than the SA-43 and about on par with the 5-way. There is excellent layering, instrument separation, and black space, with the differences between the 5-way and NT-6 pro coming mainly from note presentation. The NT-6 pro articulates the details better, presenting you with the details in an immediate way while the 5-way does things organically. The SA-43 is more laid back, so the size of the NT-6 pro, even though slightly smaller, is still impressive. But, both have their place as the NT-6 pro has a better spatial presentation for electronic while the SA-43 is best with acoustic (although both are excellent with other genres). The NT-6 pro presentation is not unlike sitting right in front of a performance, and if you close your eyes you can imagine the performance.
Note attack and decay is on the analytical side, but very capable and notes can be sustained, however they are on average shorter than most other CIEMs. The most similar in note thickness is the UE IERM, although the NT-6 pro offers better attack and decay capability, and the NT-6 pro is between the UE IERM and LS8 in liquidity of the presentation. This capability allows the NT-6 pro to sound extremely fast in an effortless way regardless of the speed of the note (Extratone anyone?). This note capability and presentation combined with the enhanced treble give the NT-6 pro exceptional clarity, in fact the best I have heard. Transparency is among the best and the drivers are very well integrated with a very coherent presentation. Resolution and detail levels are top notch; however, the ambiance that is created with a more organic sound isn’t as present since the details are brought out and overshadow some of the fine nuances in the background of the presentation. You can’t have it all. An incredible presentation focus is another strength which makes some of my other CIEMs sound fuzzy in comparison. The biggest weakness of the NT-6 pro is the tone, which is unnatural due to the enhancements, but is still surprisingly natural sounding, all things considered, due to the note attack/decay capability.
In a nutshell, the presentation is very spacious and 3D with enhanced bass and treble, but a present midrange, analytical but liquid presentation, resulting in musicality to go with extreme clarity.
NT-6: The NT-6 and pro are torn from the same cloth as they share many characteristics and with some songs you will be hard pressed to hear a large difference. Those songs are the ones with low levels of bass and treble that doesn’t extend too far, not to mention not the largest soundstage. But, there are differences. The NT-6 is the reference with a pretty neutral bass and treble combined with a balance in the midrange making for a presentation that doesn’t push any one portion of the spectrum forward. The pro, on the other hand, enhances the bass and treble region and also has a more 3D space. The good (due to the treble) is that much of the treble is brought forward, improving upon the super clear NT-6; but the negative is the tone can sound a bit off in comparison as you know the treble is being enhanced. I gave the NT-6 the highest marks for clarity, but the pro steals that honor from the NT-6.
In the bass region, the bass enhancement is slightly noticeable with light and background bass tracks, but when a heavy bass line kicks in, the pro kicks it up several notches. Since the pro is enhanced, the bass isn’t quite as clean as that of the neutral NT-6, which is due to the additional rumble. The midrange of the pro is a slight bit further back, but then there is more depth of the soundstage space, allowing the NT-6 to present vocals a bit closer and more personal, while the imaging of the pro is improved over the NT-6.
As one would expect, technically these two are quite close with the pro having a bit better transparency due to the more 3D soundstage, but the midrange and treble of the NT-6 sounding slightly more natural. Detail and resolution is ever so slightly higher on the pro and due to the boost in the treble, the coherence isn’t quite what it is with the NT-6. Dynamics, speed, and note attack/decay are the same.
Both the NT-6 and the pro version offer an extremely high technical performance with an analytical yet musical performance in different flavors. The NT-6 is excellent as a reference monitor, something you want when you want to hear all the details with great clarity but don’t want enhancements in the bass region. The pro turns the reference into a more exciting and even clearer sound with a bass and treble boost and a bit more depth to the soundstage with a slightly less forward midrange. Hidition gives excellent choices depending on your tastes.
JH16: In comparison with the NT-6 pro, the JH16 has a focus on the lower portion of the spectrum with more warmth and bass enhancement. One of the things that jumps out at me in this comparison is the clarity of the NT-6 pro, which makes the JH16 seem like there is a haze over the presentation. Size of the presentation space is about the same as far as width, but the improved depth of the presentation makes the NT-6 pro sound larger/more 3D and less closed in. With a faster note a bit more capable of sustaining decay, the NT-6 pro has more transparency and coherence with better speed, resolution, and detail than the JH16. Dynamic range is similar between the two, but the NT-6 pro does have an edge and both are about equally forgiving.
Both have bass enhancement, but it is implemented in a very different way. The JH16 has an always on bass boost with a warmer presentation than the NT-6 pro, but the NT-6 pro has more boost in the lower registers, but it isn’t something that is always on. For example, with tracks that have light bass lines, the NT-6 pro doesn’t sound enhanced at all, but with bass heavy pop and electronic, it surpasses the JH16 in boost in the deeper registers, which is from a higher dynamic range in the bass as well as the contrast of boosted bass with less mid-bass. While the NT-6 pro can generate a good amount of bass, the quality is also top notch with better articulation than the JH16.
The JH16 midrange is more forward than the NT-6 pro giving a more intimate presentation, but the clarity and focus of the NT-6 pro is superior; however this will come down to personal preference. The upper midrange has a peak on the JH16 while the NT-6 pro has a smooth transition up, and then starts to increase quickly in the treble region. The NT-6 pro is brighter and yet smoother in the treble with more natural note decay. Add extra line here
The JH16 is a fun CIEM with enhanced bass, a fairly neutral midrange presentation, and a boost in the upper region that improves clarity while the NT-6 pro is similar but different. From a technical performance standpoint, the NT-6 pro bests the JH16 due to a wider note attack and decay range that allows for better focus, clarity, and a more natural sounding note across the spectrum, but the NT-6 pro does have a V shaped sound signature (boosted bass and treble). If you like a bright presentation without a lot of warmth, the NT-6 pro is for you. But if you want the bass in every track from Barry Manilow to Massive Attack and don’t want a laid back midrange, the JH16 is for you.
8.A: While the NT-6 pro has enhanced bass, the 8.A has more warmth, richness, and power in comparison with the brighter, clearer, and more analytical NT-6 pro. Both have a 3D space, but the 8.A has a more forward presentation in comparison to the more open sounding NT-6 pro, which has a slightly larger overall soundstage presentation. While clarity levels of the 8.A are impressive for the note thickness, the NT-6 pro’s clarity due to the more analytical note, less mid-bass, and brighter treble are easily noticeable, bringing out more detail across the spectrum, but especially in the treble region. The note attack/decay differences lead to the NT-6 pro sounding faster and, of course, more analytical, and while the NT-6 pro is smooth with some liquidity, the 8.A is quite a bit smoother, lush, and liquid. Coherence is similar and bass dynamics of the 8.A are superior, but dynamics of the rest of the spectrum are better with the NT-6 pro. Transparency is close, but the NT-6 pro does edge out the 8.A due to the overall clarity, imaging, detail, and larger space. The 8.A is more forgiving of poor quality tracks as the NT-6 pro will resolve all the issues, especially in the bass region in comparison.
The 8.A conveys power and emotion with good bass authority and an always enhanced sound compared with the NT-6 pro, which has a boost that is dependent on the track. Comparing the two is track dependent as the 8.A can sound punchier and significantly more bass heavy, but other times the NT-6 pro can actually sound a bit more bass heavy. However, in the mid-bass region, there is no real contest as the 8.A has quite a bit more warmth which thickens the overall sound and provides more emphasis to upper bass notes, adding a richness in comparison. The forward midrange of the 8.A is thicker and gains clarity from layering of the soundstage; however, the NT-6 pro also has very good layering resulting in a much cleaner and clearer midrange. The upper midrange of the two isn’t too far off, but as the frequency increases, the two diverge. The NT-6 pro is bright with emphasis that brings the treble up front while the 8.A has a laid back treble that pushes it further back resulting in a different feel to the music.
With quite different presentations, the NT-6 pro and 8.A will complement each other well. The 8.A gives an enjoyable, smooth, powerful, and rich presentation that can be enjoyed both causally and intently while the NT-6 pro provides a brighter, more analytical, clear, and detailed presentation that feeds you the details in a musical way. While the treble of the 8.A is never offensive, it won’t please treble heads, but the boost in the NT-6 pro treble will turn off some with its somewhat artificial enhancement.
SE 5-way Reference: While these two don’t sound the same, there are many similarities in the overall presentation. With most tracks, the NT-6 pro sounds noticeably brighter, although the 5-way can adjust depending on the track. Clarity is close, but they have similar but different clarity. The 5-way clarity is organic and takes very little from being bright while the NT-6 pro has an organic clarity with a laser focus within the soundstage as well as accentuating the details and clarity to an extent due to brightness. This can lead to the 5-way sounding dull in comparison with the NT-6 pro, or the NT-6 pro sounding quite bright depending on the track. The NT-6 pro presentation is very 3D and spacious, slightly more so than the 5-way. Resolution is similar as is instrument detail, instrument separation, black space, and other characteristics; both are impressive. Both change with each individual track, but the 5-way does have more variation than the NT-6 pro.
The 5-way beats the NT-6 pro with a more natural tone and still the best attack-decay-sustain-release (ADSR) and PRaT, but the NT-6 pro isn’t far behind. The NT-6 pro has a greater sense of speed than the 5-way. Both are quite transparent, coherent, and have impressive dynamic range. One of the impressive things about the 5-way is the ability to handle all bitrates and music types and not sound offensive, at least not more than the original track. The NT-6 pro can be offensive in the treble region due to the emphasis with poorly mastered tracks, but chances are you won’t be listening to the poor quality tracks I have in my test file folder.
While the NT-6 pro is bass enhanced, the 5-way has more headroom in the bass as more power can be conveyed with a bit more sustainment at the expense of sounding a slight bit slow in comparison with the NT-6 pro. It is really close from a performance standpoint, and the NT-6 pro has more bass with tracks that aren’t all that bass heavy. The 5-way is a bit warmer, but it does change quite a bit with various tracks, so the amount is variable. The midranges aren’t too different until you get to the mid-upper midrange and above where the NT-6 pro has more energy. This difference in energy changes the location of the midrange depending on the track, resulting in flip-flopping in which is more forward, but in general the 5-way is more forward. Moving up to the treble, the NT-6 pro is more enhanced and while both have great quality, the 5-way edges the NT-6 pro as is readily apparent with poorly mastered tracks.
The NT-6 pro is similar to the SE 5-way in capability, but quite different in presentation with bass and treble emphasis, slightly thinner/quicker note, and more apparent clarity. While the 5-way has a neutrality to it, the NT-6 pro has a coloration to it that can be fun. Both have a wow factor for me, but with fast and energetic genres like electronic, the NT-6 pro is more fun. If you want a CIEM that performs at the highest levels, you have options!
LS8: The LS8 has a warmer, slightly more forward sound compared with the NT-6 pro which has more emphasis on the upper end. The presentations aren’t drastically different, but the LS8 is a bit more mid-forward while the NT-6 pro has a wider and deeper space that is more laid back, resulting in better imaging. While the LS8 is clear, the NT-6 pro has better clarity and the soundstage is more sharply focused. The NT-6 edges the LS8 in most technical aspects from transparency to dynamics to coherence to detail and resolution levels to speed and note attack/decay ability.
Deep bass is quite a bit more prominent with the NT-6 pro, and the capability and depth are superior. Moving up from the deep bass and the LS8 takes over with a bit more quantity that continues up the spectrum into the more mid-forward midrange, giving the LS8 a richer lower end. Moving to the upper midrange and on up the NT-6 pro is brighter yet the quality of the treble is similar, as is extension. The NT-6 pro diverges in the treble region as the emphasis grows as the frequency increases which can lead to a bit too much treble in some tracks.
Similar, but different, they are definitely different flavors of audiophile enjoyment. The NT-6 pro is brighter and has more deep bass with a more expansive space while the LS8 is more mid-forward and warmer in presentation. The NT-6 pro is a better choice for critical listening as it will resolve more than the LS8 with a better focus, but for just relaxing and listening to music the LS8 is an excellent choice.
IERM: These two definitely share some similarities, but the IERM is warmer yet duller with a more distant and less intimate sound. While the IERM has a nice soundstage size that is very 3D, the NT-6 pro is a bit larger with a better focus and imaging, giving a clearer presentation overall. The NT-6 pro sounds faster than the IERM and effortlessly recreates any speed note. Detail levels with the IERM are good, but the NT-6 pro has more micro-detail, and that detail is presented with better clarity. The NT-6 pro is more transparent and coherent and has better note attack and decay capability as well as more dynamic range. The IERM has a tendency to point out issues with tracks that the NT-6 pro still highlights, but not in quite the same overly dramatic, sometimes harsh way.
The bass is quite divergent as the NT-6 pro has enhanced bass that goes deeper than the IERM and has greater dynamic range and note sustainment when necessary, resulting in deep bass that is more prominent and also conveys more of a live feel. But, the IERM is overall a bit warmer than the NT-6 pro, although the NT-6 pro sounds much cleaner. Bass detail and texturing are better on the NT-6 pro. The midrange of the NT-6 pro is presented in a more up-front way but has more depth to the presentation with better layering. Clarity levels, instrument separation, and black space are better with the NT-6 pro. The upper midranges start to approximate each other, but moving up to the treble, the IERM has a peak where the magic and pain happen - the magic giving the IERM its excellent detail levels and the pain being a harshness that is often offensive to my ears. The NT-6 pro in contrast has more energy at higher frequencies and the overall presentation is smoother.
With different purposes, the NT-6 pro is a faster, more precise and enhanced IERM. I don’t recommend the NT-6 pro for what the IERM was created to do, monitor music in a studio, which it does very well. The NT-6 pro will add excitement and ultimate precision to your music with a similarly bright presentation, but with enhanced bass.
EM4: While the EM4 may be brighter than the standard EarSonics sound signature, the overall sound is quite different than the NT-6 pro from top to bottom. The first thing that jumped out at me when A/Bing these two is the EM4 makes the NT-6 pro sound very bright, on the thin side, and analytical. From a presentation standpoint, the NT-6 pro is a good deal wider and more spacious with close but better presentation depth giving the NT-6 pro the decided advantage for spacious and 3D tracks. The perception of depth and width does change quite a bit with tracks as the EM4 has a deeper presentation on average even though the NT-6 pro can project further. This leads to a larger sound and different airiness with tracks that have narrow soundstages. Dynamics are better with the NT-6 pro, which is faster and more immediate, and the NT-6 pro is more transparent and coherent. Detail levels, clarity, and resolution are better with the NT-6 pro, and due to a smoother, less peaky treble and more natural treble decay, the NT-6 pro is more forgiving of poor tracks.
Bass is quite different on most tracks as the EM4 has more enhancement, warmth, and overall conveyance of power with the exception of when there is deep bass, where the two are close but the NT-6 pro has more headroom and better control and about the same rumble. These two are close in placement of the midrange, but depending on the track they flip-flop in which is more forward, due to the reasons noted above. Treble of the NT-6 pro is more forward and alive with a more realistic sound that has better note decay.
If you read the above paragraphs, you probably came away thinking the NT-6 pro is better, but it is more a matter of taste and tracks. The NT-6 pro is bright and in comparison, thin. Sure, it is surprisingly smooth, but still analytical vs. the EM4, but the NT-6 pro treble really shines even with the brightness. Overall the EM4 has a more powerful and organic sound, except in the treble region, while the spacious and bright NT-6 pro is more detailed and analytical.
SA-43 (bass switch on, presence switch off): While sharing some strengths, these two are mostly different. Starting with the overall presentation, they are about the same as far as where the midrange is presented, but the NT-6 pro is slightly more forward. While the NT-6 pro is a great performer in the soundstage depth, the SA-43 outperforms the NT-6 pro both in width, by a bit, and in depth, by a larger margin; however, the NT-6 pro has a bit better imaging and focus within the soundstage. The NT-6 pro is clearer overall with better instrument separation, better dynamics and more speed when needed, but due to superior note decay, the NT-6 pro can also sustain notes quite well. The SA-43 is smoother and more forgiving of poorly mastered tracks, while the NT-6 pro has much better instrument detail and a bit more refinement within the soundstage.
With the SA-43 bass switch on, the SA-43 has more bass and warmth than the NT-6 pro except in the deep bass region where the NT-6 pro doesn’t have the roll off and shows much more capability, adding a prominent feel to the bass that the SA-43 just manages to touch on. The NT-6 pro bass is more controlled and detailed than that of the SA-43. With a more laid back and organic midrange, the SA-43 is more relaxed in presentation, and when the presence switch is turned on, the midrange becomes thicker and more “cloudy” in comparison with the ultra-clear NT-6 pro. Vocals are more up-front, clearer, and detailed, but due to the more prominent upper midrange, the tonality is slightly higher pitched than sounds natural, giving the nudge to the Sa-43 in that regard. Both have high quality treble, but the NT-6 pro is much brighter and can lead to too much comparatively, from a realistic tone standpoint. The SA-43 has a different decay of the treble that sounds more natural, but dull in comparison.
These are two very different sounding CIEMs that both have a strength in the spaciousness of the presentation, but the SA-43 sounds more organic vs. the analytical nature of the NT-6 pro. Given the right source material, both excel in imaging, soundstage size, instrument placement and separation, but with different surrounding qualities, the NT-6 pro fits faster music such as electronic and metal while the SA-43 is best with acoustic. In addition, the SA-43 is organic and dull in comparison with the exciting and very bright NT-6 pro, and the decision between the two should be quite clear cut.
T1 Live!: With differences galore, the organic T1 Live! has a more realistic tone and presentation to it in contrast with the bright, bass enhanced, and clearer and more detailed NT-6 pro. Both have 3D presentations, but the NT-6 pro out-3Ds the T1 Live! with a more spacious presentation overall. The presentation is different as the NT-6 pro has a larger overall size, especially in the width department, leading to different soundstage proportions. Dynamics and speed are better with the NT-6 pro giving it a more lively sound than the more organic and natural sounding T1 Live! Detail levels are higher with the NT-6 pro while transparency and coherence are close between the two. The T1 Live is more forgiving of poor tracks.
The enhanced bass of the NT-6 pro can make the T1 Live! sound like it is lacking bass power, as it doesn’t have the rumble or punch even though it isn’t bass light. With more warmth and a slightly thicker note, the T1 Live! has a richer sound overall and a different tonality to vocals due to what sounds like a bump of the T1 Live!’s midrange, and then a contrasting upper midrange. The treble of the NT-6 pro has quite a bit more detail to go with its prominence, yet the quality is a bit superior to the T1 Live! due to a more natural decay.
With a quite contrasted sound, the T1 Live! and NT-6 pro complement each other, and you will either like them for their strengths, or be driven crazy as these two can point out weaknesses in the other. The T1 Live! has an organic sound with great presentation depth and works as an audiophile CIEM as well as a stage CIEM. The NT-6 pro is more dynamic, exciting, engaging, but less accurate. I would recommend the T1 Live! for acoustic music and the NT-6 pro for electronic, and while both can do the other genre quite well, there are some weaknesses.
Volume performance: Performance at all volume levels is quite good as the enhanced bass helps get the bass driver moving with very low volume levels and the sound signature is retained as much as it can be, taking loudness curves into account. At louder volumes, very heavy bass tracks can get a bit distorted, but I can’t listen for longer than a second of so, and can’t imagine people would have hearing in a year listening at those volumes. Even at loud volumes, there is absolutely no congestion.
Sound Summary: The NT-6 pro is somewhat complex to describe, as the ability to project sound leads to different presentations depending on the spaciousness of the tracks. In general, the NT-6 pro is bright with enhanced deep bass and an analytical yet smooth and fun sound. It isn’t smooth in the way that the Rooth lineup is smooth, as that is more of a liquid smooth. The NT-6 pro smooth is due to very good PRaT, with great capability to recreate a note with the proper attack and decay, although there is a slightly faster attack/decay than the more organic sounding CIEMs such as the 5-way, 8.A, and SA-43.
The midrange is neither recessed nor forward in general, but the majority of my tracks are slightly more forward than laid back. Extension on both ends of the spectrum is very good and the bass is tactile and as powerful as some of the other very good performers such as the EM4 and 8.A, but with less warmth. Due to the enhanced deep bass, the bass isn’t as cold as that of the NT-6, the added spaciousness compared with the NT-6, and the more exciting sound make me want to listen to the NT-6 pro for extended periods of time; something I didn’t always want to do with the NT-6 even though it is more tonally accurate.
It should also be noted that the NT-6 pro has the best clarity of any headphone I have heard to date, articulating every note and detail in a way that is extremely easy to comprehend, and the musical presentation makes it enjoyable, for the most part. The biggest detractor to the sound is the enhanced upper end which, depending on the track and your treble tolerance, can at times be just too much. I would imagine those particular tracks were made for low-fi equipment as they are usually larger artists (Queensryche for example). There are plenty of tracks that don’t have this issue.
Overall, if you like bright and want incredible clarity, great spaciousness, and enhanced deep bass, the NT-6 pro will hit the spot!
Portable Sources, DAPs
Clip+ (rockboxed): The Clip+ sounds quite good with the NT-6 pro with a clear and precise presentation retaining the sound signature and giving quite good detail and 3D spaciousness to the presentation. Overall for the price this combination is very good. 6/10
iPhone 4S: While the 4S doesn’t sound bad, having good clarity and detail levels, it doesn’t have the dynamics, clarity, or depth of presentation of the Clip+. The midrange is also brought a bit further forward than with the Clip+. 4/10
RoCoo BA: The RoCoo BA is similar to the Clip+, but does have differences. There is slightly less deep bass, the overall presentation is slightly more laid back and a bit wider, and there is a tiny bit more detail and better focus, however the differences aren’t all that large. 6.5/10
801 (with GAME card): The 801 brings the presentation of the NT-6 pro forward and gives a sound that is closer to the iPhone 4S than the DX100 or Clip+. Detail and spaciousness are taken up a notch from the RoCoo BA and Clip+, but the overall presentation isn’t quite as clear, having a warmer sound that is a bit veiled in comparison. If the NT-6 pro is too bright and you want a more up-front midrange, the 801 will get it done while giving you an expansive soundstage, but at the expense of clarity. 4.5/10
DX100: Wow, the DX100 has excellent authority, clarity, and space with dynamics to spare! This is a match that works quite well, and if it wasn’t for the 627 amp, the DX100 would be the top performer with the NT-6 pro. Not only does the DX100 perform well with the NT-6 pro, but the layering/depth of the performance is quite impressive challenging the best I have heard. Music comes alive within the large, well defined 3D space and I have spent many later than I wanted nights due to this combination. 9/10
Portable Sources, DAPs with Amps
iPhone 4S ->
i.Fuzen amp case: The HPO is brighter and clearer than the i.Fuzen, providing better clarity and the appearance of more detail. The HPO is more airy and spacious and tonally sounds more accurate. While the i.Fuzen isn’t bad, it isn’t preferred and is not a step up from the HPO, but a slight downgrade. 3.5/10
EHP-O2: The O2 gives the NT-6 pro a strong bass emphasis with a mid-forward presentation that is not all that smooth, but more analytical and digital sounding than the much smaller RoCoo BA. The iPhone HPO sounds more open and lively, although the bass isn’t as well controlled or as prominent. 2/10
Neco V2: Much more revealing than the O2 with a similar balance and tone to the HPO, however the HPO does sound a bit more open. Detail levels are higher and bass is a bit more prominent and controlled with better definition and the treble is a slight bit smoother with an overall better refinement. Not a huge improvement, but an improvement. 4.5/10
Shonyun-306: The 306 adds a bit of refinement to the V2 presentation with a well controlled bass that matched well with the NT-6 pro and has a very natural presentation that is more open and airy with a more realistic reproduction than the O2 and V2. Unfortunately the 306 has hiss with the NT-6 pro, although it isn’t very significant, reducing the score by .5. 5/10
uHA-120: With a sound that is a bit more open than the brighter 306, the 120 has a nice presentation of the lower half of the spectrum, but the treble region isn’t quite as refined as the 306 which can lead to a bit harsher sound in direct comparison. The soundstage is a bit deeper than the 306 but not as wide. 5/10
Arrow 12HE 4G: The 4G adds some space to the presentation of the NT-6 pro in comparison with the 120, 306, V2, and O2, yet is a bit more forward. The presentation is smooth and refined and the slight bit of added warmth is welcome; however, deep bass isn’t as prominent as the other amps. Overall, the quality is better than the previously mentioned amps due to the increased refinement. 6/10
Pico Slim: The PS emphasized the upper midrange of the NT-6 pro, giving a different tonality and an odd forwardness to the presentation. The emphasis, while not all that bad, doesn’t sound detailed and refined, and bass isn’t as impactful or realistic as other amps. This is not a great matchup. While the presentation is of better quality than the HPO, it isn’t as significant as the price of the PS. 5/10
Stepdance: The SD has a bit more treble emphasis, but less upper midrange/lower treble emphasis than the PS, and the sound is overall more refined. Soundstage space, while deep, isn’t as wide as I am used to with this amp and about on par with the PS. This is an OK match, but not great. 5.5/10
Cruise: Dynamics jump out at you with the Cruise, and the true sound of the NT-6 pro comes through. Detail levels are high considering the iPhone is the source, and the soundstage is wide and deep in comparison with the other amps. Bass has just the right emphasis and treble is about on par with the SD, but more refined and enjoyable. When music is playing, the fast yet natural sounding Cruise is a good match, however, there is hiss, and more hiss than the 306 which results in a 1 point deduction from the score. 6/10
627: The 627 gives the NT-6 pro more body than the other amps, adding a thickness compared with the Cruise which does take away a slight bit of clarity (but there is still plenty to go around). The overall sound is darker while the presentation is more spacious. Due to the increased width of the soundstage, the relative depth isn’t as great as some of the other amps. The overall sound isn’t quite as precise as the Cruise, but the bass control is top notch. 6.5/10
Modded iPod ->
EHP-O2: The O2 is significantly better with the modded iPod than the iPhone 4S. There is great depth to the presentation, good space, and music sounds musical. Bass isn’t overblown and the sound is natural with enough treble that is smooth. 6/10
Neco V2: With this source, the V2 doesn’t have the refinement of the O2, the presentation is more mid-forward with less depth, and the overall sound isn’t quite as musical. Overall, the treble tone sounds slightly off. 5/10
Shonyun-306: The 306 has more of a V shaped sound sig in comparison with the V2 and is more refined, open, and musical. The sound is quite close to the O2, however the O2 hold an ever so slight advantage due to the slightly tamer treble resulting in better tonality. The 306 does have a hiss issue, reducing the score by 0.5. 5.5/10
uHA-120: The presentation is brighter than the 306 and the treble isn’t quite as refined, but the overall presentation is more transparent. Spatially the 120 performs quite well and is convincing, but the O2 and 306 are slightly more spacious and in direct comparison, the 120 doesn’t image quite as well. 5.5/10
Arrow 12HE 4G: The 4G adds a slight warmth, but is average in width and not quite as deep as the competition. Deep bass isn’t as extended as with the other amps although the refinement is quite good. Due to the limited depth of the presentation, the 4G isn’t as convincing as some of the other amps. 5/10
Pico Slim: With a bit brighter sound and similarly sized soundstage to the 4G, but slightly deeper, the PS doesn’t do anything wrong, but doesn’t do anything better than other, lower cost amps. The refinement is very good however, so the presentation is not harsh at all. 5/10
Stepdance: More open and slightly more spacious than the 306 and O2, the SD also surpasses those with better refinement. The SD has well controlled bass that can really punch, but the sound is more laid back than in your face. 6/10
Cruise: Punchy and fast the Cruise sounds very clear and emphasizes the strengths of the NT-6 pro. More spacious than any of the other amps except the 627 in both width and depth, the Cruise would be a great match for those that want that fast, precise, clean, and clear presentation. But, the hiss is an issue as it can sometimes be heard in quieter songs, which caused me to reduce the score by 1 point. 6.5/10
627: The 627 has an excellent tonal balance with the NT-6 pro to go with refinement, depth, width, and layering. This is an excellent combination that gives the NT-6 pro body, depth, and a more organic and natural sound than the other amps. And yes, this sounds better than the 801-> 627! 9/10
EPH-O2: The O2 input is overloaded by the output of the 801, distorting the sound. 1/10
Neco V2: This combo is very similar to the 627, with the major differences in the bass power and fine layering within the soundstage, but close enough. 7/10
Stepdance: Similar sound to the 627, but not quite as open or 3D, and has a bit more congestion. 5/10
627: Connecting the 627 between the 801 and NT-6 pro lifts a veil and adds space to the presentation both in width and depth. The midrange isn’t as forward, but still more so than the DX100 line out, and the bass is quite a bit more prominent, giving a fuller presentation with better control and the whole spectrum has more detail and refinement. The overall presentation refinement isn’t on par with that of the DX100 -> 627, but it does improve the presentation and change the sound quite a bit. 7/10
627: The DX100 sounds spacious with the NT-6 pro, but when you plug the 627 between the DX100 and NT-6 pro, you are rewarded with even more space and layering as well as more bass authority and a sense of better control. The DX100 controls the bass exceptionally well, but the 627 just does something else that adds to that. The treble is a bit smoother and the overall presentation goes from extremely musical to extraordinarily musical! While the differences aren’t night and day, they are appreciated 10/10
HUD-MX1 -> Shonyun-301:This combination is very good as the MX1 does have nice resolution and a good soundstage space while the 301 is just a great match for the NT-6 pro as it accentuates the exceptional size of the presentation. The overall presentation is punchy, dynamic, and has a musicality to it. It is not overly bright and the amp just performs. Upgrading the DAC does help, but not too much. 9/10
D1 -> Shonyun-301: The D1 improves upon the resolution and bass response of the HUD-MX1 when used with the 301, and tonality is more accurate as the midrange is slightly less bright. 10/10
D1: The D1 is a step up from the 801 with a cleaner, brighter presentation with less thickness. There is more bass presence than the 801 and less midrange focus. The presentation is close to that of the DX100, but a bit brighter with more width but less depth to the presentation. The added brightness pushes the presentation a bit too much to the bright side for me and reduces the magic that the DX100 has, but only by a small amount in comparison. Be prepared for bright with this combination! 8.5/10
Source Summary: The NT-6 pro changes quite a bit with different sources, so finding the right sound for you can take some trial and error. The quality of the DAC section does help with detail and resolution, but especially in achieving the presentation depth and width the NT-6 pro is capable of. For some reason the latest software for the 801 is a horrible match; however, all other DAPs/DACs I have tried don’t have the same issues. Using a good amp also helps where it comes to spatial presentation; however, the small changes to the upper midrange and treble did lead to significant tonal changes. Select your source carefully and be prepared for some trial and error.
Boasting 6 balanced armatures in a 5-way design, the NT-6 pro is very capable of amazing sound across the spectrum. The sound is on the analytical side, but with some liquidity and musicality. Both ends of the frequency spectrum are enhanced at the extremes, but the midrange is not recessed, and the sound does not have the typical warmth that comes with enhanced bass. The sound is on the quicker and punchier side with excellent dynamic range, transparency, smoothness, and plenty of speed for any genre, but still enough note decay for a natural sound. Clarity and presentation focus are in a class of their own and help present every detail within the music clearly and concisely.
While the NT-6 pro sounds good with lower end sources, carefully selecting a quality DAC and amp or DAP will result in an improved performance. From a technical standpoint, the NT-6 pro is one of the top three in performance of my custom IEM collection and I highly recommend it if you like a bright, engaging, fun, ultra-detailed and clear sound.
- Extremely large presentation space with a very 3D presentation
- Top notch clarity and detail levels
- Great combination of an analytical sound with a musical performance
- The bright sound affects tonality resulting in an unrealistic sound at times
Edited by average_joe - 9/20/12 at 10:01pm