[Alexis13]

  Maybe the Etymotic ER4. Not detachable but pretty neutral from what I heard.

Added to my list. Thanks a lot, have you used them before?

 

[Alexis13]

  Sony EX1000 or 7550?

In fact I think also about Sony, but cheaper model EX600. What do you think?

 

[NoobAThome]

  In fact I think also about Sony, but cheaper model EX600. What do you think?

The EX600 gets you about 80% of the EX1000 if I have to put a number on it but I havent heard it for a while so take it with a grain of salt. The 7550 or EX800ST for japanese domestic market version is essentially the same as the EX1000 but with a 3 dB reduction in the treble above 6 KHz (I think) and is may favourite of the 3. Doesnt sound as harsh whilst still retaining the balanced/neutral signature. 

 

[Rozenberg]

You can find used Noble 4 in great condition for ~$300 like for example here or here
They pop up kinda often these days.
 
I'm an owner of Noble 4 too, yes they are uncolored and really detailed, with little bass.
You gotta get a good seal if you want to feel the bass

 

[milford30]

   
+1. The W30 are far from being neutral at all, they have a nice mid bass hump and bright highs along with slightly recessed mids, a bit like the TripleFi 10 or the HD25.
 
The sound carries rather a lot of detail, though.

 
w30 have a very slight v shape, well toned down from w3, and are not farm from being neutral. There is a difference between the W30's bass, sharp and no bleeding into the mids vs the thumping boom 'bassy' headphones. 
 
I don't hear a mid bass hump, actually no bleed into the mids, TF10 does not have recessed mids.... read clientOS' comparison to the re0 below......
 
 
Frequency curves are relative read clientOS' review on the re0, and how he compares them to the TF10:
 
http://www.head-fi.org/t/383355/review-head-direct-re0-a-new-contender-for-the-best-iem
 
Detailing of the re0 partly comes from the treble, which is definitely lost on the w20.
 
Read comment about W30 bass above.
"Bass often comes and goes too quickly to give the sense of fullness. On the plus side, RE0 does have enough impact on its bass."
 
 
 
 
If you are going that route of absolute flat response, you're only choise is the ER4S

 

[Voyageur]

  Maybe the Etymotic ER4. Not detachable but pretty neutral from what I heard.

 
+1! I'm not willing to hype up Etys, but to me they're still unrivaled in their price bracket when it comes to pure SQ. You might not like the looks of them though.
 
The cable is tricky to replace by yourself, but it is made possible thanks to an adapter.
 
(I reviewed them here: http://tinyurl.com/or6pfxg)

 

[Alexis13]

At the end my list is like this (in order of my preference):
1. Noble 4 (Wish it a lot and seems that is really what I need, but the price of 450USD is a little bit too much, just now I'm looking for some used item, any suggestions?)
2. InEar StageDiver 2 (SD-2) (Like all except the price, trying to find out a good used item)
3. Sony MDR-EX600 (I think if Noble 4 will not come to me from smb who wants to sell it for around 300USD I'll proceed with Sony).
4. Etymotic ER-4 (Still have a doubt about non detachable cable, but keeping in mind a good service of Etymotic)
5. Nuforce Primo 8 (Like the price of about 250USD, design and sound, but afraid of a bad build quality)
6. Ultimate ears UE900 (Like the design, build quality and price, but not sure about sound signature - seems it is more V-shaped than balanced)
7. Fidue A83 ( (Like the design, build quality and price, but not sure about sound signature - seems it is more V-shaped than balanced)
8. Earsonics SM2 ifi (I'm not sure about their sound quality, but design and price is quite good for me, and seems that their sound sign. is balanced)
 
 
I understand that maybe some of these options are not really neutral and balanced, but i can not purchase any earphones that I don't like as they look even if they sound great.
 
I appreciate any other options for less than 400USD.

 

[Toom]

Whats wrong with V shape?

 

[JackRevenant]

 
3. Etymotic ER-4 (Still have a doubt about non detachable cable, but keeping in mind a good service of Etymotic)
 

The ER4's cable is replaceable, and it's pretty solidly the best choice for a neutral IEM under $400, in my opinion. The ergonomics are a bit mediocre - over-the-ear wear is difficult - but the isolation is stellar, the sound is extremely neutral and detailed, and it's a well-built, well-designed IEM in general.

 

[Alexis13]

  Whats wrong with V shape?

Just not my taste, don't like a lot of bass, I prefer to hear the music as it is, without any colouring.
I like to hear the instrument, classic and vocals.

 

[Alexis13]

  The ER4's cable is replaceable, and it's pretty solidly the best choice for a neutral IEM under $400, in my opinion. The ergonomics are a bit mediocre - over-the-ear wear is difficult - but the isolation is stellar, the sound is extremely neutral and detailed, and it's a well-built, well-designed IEM in general.

Noted, begin to like it more and more. Thanks

 

[JackRevenant]

  Noted, begin to like it more and more. Thanks

Happy to help. If you haven't already read it, I recommend giving ljokerl's review of them a look. http://theheadphonelist.com/headphone_review/etymotic-research-er-4s/

 

[NoobAThome]

Maybe take a look at the Audio Technica IM-02, also quite neutral and balanced.

 

[getclikinagas]

 @Alexis13 If you like the sound of the RE0, you probably prefer an analytical sound signature. The RE400 with it's relatively warmer sound and relaxed upper end is not the logical next step.
If you can find an RE272 floating around it is worth a shot with your preferences. But build quality is questionable.
 
I too am, searching for an upgrade to my RE400 and RE272. For the RE400, I am currently looking at the Aurisonics rockets.
Finding an upgrade to the RE272 is proving to be quite difficult,especially at the 200-300$ price range. Also I am looking for some added bass impact while maintaining the clarity and detail levels of the RE272. The most interesting IEM in this search was the FLC technology FLC8 which comes in at 300$. Check out ljokerl's review of the same here.
 
Here's an interesting quote

Equally impressive is the clarity of the FLC8 – the mids, while not at all forward in the stock configuration, can’t be called recessed either and are impressively close in clarity to high-end analytical earphones like the Brainwavz B2 and VSonic VC1000.The FLC8 is noticeably clearer than the very capable TDK BA200, EarSonics SM64, and Philips Fidelio S2. There is no upper midrange dip as there is, for instance, on the SM64 and Fidue A83, which allows the FLC unit better crispness and overall resolution, as well as superior vocal intelligibility.

Also this comparison with the A83

The bass of the FLC8 is a little tighter while the A83 is a touch more impactful (I think it has more of a mid-bass hump).
The biggest difference is that the FLC8 lacks the upper midrange dip of the A83. This makes it a little less forgiving on some tracks (especially when it comes to sibilance), but helps with the clarity, crispness, and detailing and makes it appear more neutral and balanced.
Tonally the A83 is warmer and its presentation is a little more laid-back.

 
But, he also mentions this:

I don’t really consider it a neutral IEM – the bass is definitely lifted (somewhere between mild and moderate, I would say) and the treble has some extra energy – definitely more than the RE-600, but maybe just short of the EX600.
 
For many listeners they will be the best, but for instance for someone who’s looking for a flatter type of sound the ER4S from Etymotic would be better, and someone who likes warmer, smoother sound signature will be much better off with a FitEar TG334 or EarSonics Velvet (or even SM64).

The multiple tuning options could get you even closer to your preferred signature. Try posting on his thread here. He will be able to give you a few suggestions.
 
PS: Please note that I do not own the IEMs mentioned above (except for RE400 and RE272). I, like you, am on a similar quest. I just thought I'd share my findings.

 

[Alexis13]

  Happy to help. If you haven't already read it, I recommend giving ljokerl's review of them a look. http://theheadphonelist.com/headphone_review/etymotic-research-er-4s/

In fact Im trying to choose based in his list (looking at iems with SQ above 9.2).