So after having gotten my hands on the revised version of the NS-U1 (sound has been tweaked; the new version can be recognised by the new colour scheme (blue or grey instead of chrome)) one and a half weeks ago, I'd like to share some impressions with y'all.
Let me start off with my experience with the NSC-01 cable (stock NatroSound cable): Listening to to the IEMs with disabled NS, mids and highs are pretty balanced (with a moderate preference of the upper mids) and there is no unnecessary bloom in the fundamental area. The bass emphasis starts pretty low and forms its climax considerably lower than most other in-ears (NS-U1: ~ 80 Hz), wherefore the bass doesn't bleed into the lower mids at all but really just concentrates on the midbass and sub-bass. As a result, there is also no thickness in the fundamental range and upper bass (at around 100 Hz) is not overly firm. The implementation of the bass emphasis is really nicely done and the lows are also relatively nimble, quick and arid for dynamic drivers. Imaging is also quite nice and the NS-U1 would already have been a nice single dynamic driver in-ear without the NatroSound crossfeed implementation.
Speaking of NatroSound: switching NS to "ON", tonality changes audibly: gone is the fundamental-bleed-free midrange - overall bass gains quantity, but also the fundamental range along with the lower mids sound noticeably thicker, resulting in warm, coloured mids. Hrrrrrr grrrrrr... As for the added fundamental bloom, it also makes the sound appear muddier and less refined (I'll get to the soundstage with enabled NS in a few lines when I write about the NSC-03 cable). Nope, I am not much convinced about the tonality shift with engaged NatroSound when using the standard cable. Without NatroSound (stock cable), the mids are fairly balanced and clean, without any fundamental bloom at all. With NS, they become overly dark (clearly to the extent that I'd consider them being obviously coloured). Maybe suitable for those who love very warm mids, but not for those who prefer a balanced midrange presentation. With the stock NSC-01 cable, I personally only like the NS-U1 with disabled NatroSound (because of the overly warm midrange with engaged NS).
But there was that upgrade cable called NSC-03 I mentioned, right? Let's look at that one: we have a bass dial, an NS dial as well as an NS switch. With disabled NatroSound, not much surprising, the second NatroSound driver is not engaged, so the NS dial won't show any effect - but the bass dial does, and how it does! Pretty cool, NS-U1's sound can be modified from being bass-light and clearly mid-centric to being quite bassy (bass level is similar to NSC-01's level with disabled NatroSound but moderately more warmth in the root).
Now turning NatroSound on with the NSC-03 cable, I am really glad that Tatco invented it: with engaged NS, the fundamental range and lower mids also gain some more warmth, but as we have both a bass and an NS dial, the amount of warmth can be perfectly adjusted to one's personal preference. And as the fundamental bloom can be tamed down and even eliminated with the right configuration of the NSC-03 cable, the level of details also doesn't decrease as much as when using NS with the NSC-01 cable.
And now some words about NatroSound (since I can finally appreciate it because of the NSC-03): first off, I was never the person who was the biggest crossfeed fan and also don't find it necessary
for me. LEAR's NatroSound also doesn't entirely change that (i.e. you won't find me running down the street completely naked with nothing but a DAP plus these in-ears and telling everybody I see how NatroSound changed my life and the way I listen to music), but there is one extremely pleasant thing I noticed about NS (more about that in a second). So what does NS do apart from adding warmth to the sound and extracting some of the left channel's information into the right one and vice versa? What I am hearing is that the presentation of vocals becomes more intimate, but also that the forward projection is increased (as a side-effect, the width isn't perceived as much as before anymore). Really nice enhancement of forward projection (NS shows some forward projection similarities to ifi Audio's crossfeed however ifi Audio's is more precise but doesn't improve the "rear projection" (more intimate vocals) as the NS-U1 does). That is kind of nice on itself, but what I have also noticed in addition is that with enabled NatroSound, it seems like my brain faces less fatigue as it has less work to do - apparently it seems like the spatial information it needs to process with NS are similar to when hearing my regular surroundings. Yep, I am definitely noticing that my brain is less active and therefore less exhausted after really long listening sessions compared to disabled NatroSound or when listening with other headphones. It's not that I really noticed at all that my brain is exhausted or so when listening to music with "normal" in-ears and headphones, but with engaged NatroSound, I notice less fatigue (your mileage may vary).
Some very brief comments vs the LHF-AE1d: the LHF-AE1d is an exceptional single dynamic driver in-ear at around $200: very natural, authentic and realistically sounding, really good midrange plus treble details as well as good and natural imaging; its only sort of flaw is the somewhat slow bass. NS-U1 doesn't full reach AE-1d's levels of midrange/treble resolution and naturalness, but convinces with a really solid performance on its own, sporting a quick and pretty arid bass response (for a dynamic driver), good sense of space and an overall still good level of details and naturalness that is somewhat better than some single dynamic driver competitors at the same price point.
Full review by me to be followed eventually by the end of this month.
