HIFIMAN RE-600 Songbird


  • Driver Unit: 8.5mm Dynamic
  • Frequency Response: 15Hz-22KHz
  • Impedance: 16 Ohms
  • Sensitivity: 102 dB/mW
  • Weight: 0.48Oz (13.7g)


The RE-600 accessories pack will depend on whether purchased alone or bundled along with the HM-700. In my case I got it with HM-700, so the accessories are more limited. The pack includes:
  • 1 x Small single flange tips in black color
  • 2 x Small bi-flange tips in black color
  • 1 x Medium bi-flange like tips in black color
  • 3 x Single tips in different shapes/sizes in white/clear
  • 1 x Large Hifiman's own bi-flange tips in black
  • 10 x filters replacement
  • 1 x Cable wider
  • 1 x TRRS-to-TRS adapter (only in the RE-600 version)

[NOTE: The sold alone RE-600 and RE-600s include more (black) eartips quantity and 2 pairs of Comply Foam tips in 2 sizes as well, and a clamshell carrying case. - For the price they should have been included in the bundled HM-700 + RE-600 pack as well.]

Build & Design:

The previous RE-400 was already the better built one from HIFIMAN. From the outside, the newer RE-600 model looks the same, with cloth covered cable from the plug to the Y-split and the softer and rubbery material cable at the upper half. Internally they differ noticeably, as the RE-600 implements a Kevlar reinforced cable that will make it stiffer and memory effect prone, but also more durable.
As for the housing design, it's identical to the RE-400, small straight barrel but in glossy piano black which makes it look more sleek and attractive.

Fit, Comfort and Isolation:

Flawless. As simple as that. The RE-400 became one of my daily use in-ear not only for the sound, but also, and not less important, for the flawless straight design. Identically, the RE-600's design provides an easy and perfect fit, practically impossible superb comfort and surprisingly high isolation for fairly noisy ambient. While the RE-400 carries an acceptable level of microphonics, the stiffer and less pliable RE-600's cable is a bit more noisy. Something easily fixed with just a shirt clip, but should be yet better for the higher model price tag.


Even though the new HIFIMAN RE-600 is quite easy to drive, even easier than the RE-400 model (32ohm Vs 16ohm), it has proven to be fairly source dependant. It's not just the unique feature of being able to be driven either single or balanced modes, which are already very different, but even in each option it shows different results, making it one of the most versatile earphones I've got to listen to lately. As such, it's not easy to describe an exact sound signature without making reference to the source in use. One thing is for sure, the RE-600 carries the HIFIMAN's house sound and in its best way ever heard.

Part 1: Single ended (w/included TRS-TRRS adapter)

Let's start with the single ended form. The equipment used were a Sandisk Sansa Clip+ and the Panda Amp-S (w/Clip+).

Take #1: Clip+ (un-amped) - Great Midrange

Despite being a small and not very powerful DAP, the Clip+ showed no problem to drive the RE-600 in its single form. It even needed a lower volume level than the 32ohm RE-400 required; still far from being capable to show the best of the RE-600 true power, but yet noticeable better than the RE-400.
The sound is mainly mid-centered keeping a good balance between upper bass and lower highs. The mids are already excellent as expected from HIFIMAN IEMs. They're very articulated and very effortless, with the right weight at lower mids, and brightness at upper ones. If the RE-400 midrange was already too good not only for the $100 price, but even among pricier $200 sets, in texture and sweetness, the RE-600 model shows a noticeable improvement in the whole midrange dept.
If there was something that was truly impressive about the RE-400, was the vocals presentation, as one of the best among the $100-200 price bracket. The RE-600 takes vocals to a higher level with incredible more life-like quality with the perfect weight for male singers and endless extension for females ones.
So far, it's the 'bassiest' HIFIMAN in-ear, with stronger mid-bass impact and 'hotter' treble (only in comparison to the previous HIFIMAN models, that's all). While the RE-400 is probably more intimate, captivating and smoother than DN-1000 or R-50M, it couldn't match the TWFK drivers air and openness, and most importantly, their detail. The RE-600, even when single ended, not only matches those BA drivers in detail retrieval but also maintains the beautiful midrange texture and better dynamics and coherence.
Soundstage feels still closed in this single-ended configuration, and imaging isn't the best either, but the RE-600 has an amazing depth, and keeps improving with the better source.

Take #2: Amped - Panda Audio Amp-S (w/Clip+) - Dynamic Multi BA Sound?

The Amp-S is a very powerful portable amplifier (or maybe ultra-transportable, to be more exact) with opamp rolling and 2 Mode options (up to 4-chips at a time!). While I hadn't tried other chips than the stock LME49860 opamp, I could try both modes. Either way it has very solid audio characteristics: reference/flat response, wide soundstage, depth, extension, detail and accuracy, and high speed, with a somehow fairly analytical character. It doesn't accept balanced outputs so there's need to use the included adapter to be able to drive the RE-600. While the RE-600 is very efficient, it didn't show any hiss or noise from the Amp-S.
Surprisingly (and it's a huge surprise), the Panda Amp-s strength is capable to transform the HIFIMAN RE-600 into a more than amazing earphone; a true hi-fi top-tier, which challenge the best multi-BA and hybrids in-ear models.
While there's no doubt the RE-600 really scales very high from balanced sources, the Amp-S + RE-600 combo is a very special and unique one, featuring the best characteristics of both driver types, dynamic and balanced armature in just one single (8.5mm) dynamic driver.
Extension on both ends is perfect; bass reaches really low without any effort, extremely tight and yet strong. Not a bassy/warm signature (not in the current opamp) but doesn't lack of quantity. Highs are bright with zero hint of grain or sibilance. The TWFK based IEMs have a much 'hotter' and less forgiving treble, while the RE-600 remains relatively smooth even at higher volumes. Dynamics are excellent, something that multi-BA sets can be lacking, and presentation and imaging are better than hybrids sets which usually show certain degree of incoherence. The sound is very, very airy, and speed is ultra high thanks to the Amp-S power.
There's no need to mention the midrange quality; very open and articulated and obviously highly detailed. A bit more towards to the cooler side, but ultimately will depend on the op-amp chip and the selected amplifier mode.

Part 2: Balanced mode

Here's where things get interesting. Like the previous HIFIMAN in-ear generation, the new RE-600 model also comes in a TRRS balanced connection. There's also a single TRS version, the RE-600s model, for those who don't have (or plan to) a balanced output source.
My impressions are based on, obviously, the new HIFIMAN HM-700 player, and also the Firestone Fireye HDB portable amplifier, which to my surprise is able to drive both single and balanced 3.5mm ended earphones (and square 4-pin as well). Both sources will show the true RE-600 strength.
Overall, the sound is, as expected, 'balanced' with really impressive extension, stage and realism. It sounds much more natural and lifelike with a perfect balance, excellent speed, attack and decay, with special out-of-the-head feeling that's not usually found in IEMs. It may not sound as big and powerful as some hybrids models, but it does sounds much more coherent and with forward and realistic mids than those V-shaped (slightly) sets tend to present.

HM-700: (from the HM-700 review)

The HM-700 is able to take the RE-600 to a total higher level transforming it into a new beast. The soundstage is really huge with an amazing out-of-the-head feeling that's hardly found in the IEMs world, and together with the incredible depth and three-dimensional presentation and resolution and higher speed (which is actually up there with the fastest BA models) makes the RE-600 one of the best IEM out there. Sure, $500 is fairly pricey but it really pays off as one of the best sounding portable equipment.

Fireye HDB: (from the HDB review)

With the HM700, the RE-600 offers a perfect balance from low to highs with great extension in both ends. While, the RE-600 is the least light in bass from the HIFIMAN in-ear line, is more than amazing when listened from the HDB. The low end is substantially more convincing with very good rumble and deeper sub-bass reach. The midrange might show huge improvement in texture, but that's because the RE-600 is already perfect in this area; yet, the mids can be more enjoyable. The soundstage also feels wider.


Balanced X Balanced: RE-600 Vs RE-400B

While the single-ended RE-600 did show a better overall sound quality than single RE-400, they also sounded different in signature. Now, when compared the balanced RE-600 to the RE-400B is more fair to say it's a true upgrade over it. The RE-400B out of both the HM-700 and FSA HDB is much more balanced than in its single version, with slightly but noticeable boosted bass amount, more present and extended treble and better clarity overall. The RE-600 as mentioned above, takes everything to a higher level with better resolution, quality, micro-detail and practically, everything else.

Final thoughts:

With a flawless comfortable design and improved build quality (at least for the HIFIMAN Company) and mainly a Perfect Sound, HIFIMAN had released another excellent product which deserves to be called the new company's flagship. The retail $400 price is no joke, but so is the sound quality that the RE-600 offers. The RE-400B still remains one of the value earphones and bang-for-buck, even the regular RE-400 version, while the RE-600 is a true high-end masterpiece and best of HIFIMAN up-to-date.