iFi iDSD Signature

Hooga

100+ Head-Fier
Pros: Extremly good DAC performance, top class in mobile devices category
High quality upsampling applied by GTO firmware sensibly improves reconstruction quality on sub-hires material
Very good AMP quality in mobile devices category
Unique easy AMP reconfig capability optimally match extremely diverse driver needs
Nice 3D+ crossfeed option
XBass+ option may be welcome by some to add some bass body back
Cons: Too basic USB dejitter / regen features
Extremely tight transients and supercontrolled bass reconstruction – especially on GTO firmware – may be not everyone’s preference
Too tiny battery status led
Lack of third party (and even native brand) accessories to fully exploit S-Balanced ports
Not inexpensive
Micro iDSD Signature is the latest evolution of the iDSD series. Its predecessor Micro iDSD Black Label is widely regarded as a great device which contributed to building out on the expectaction regarding its evolution.

I did take my sweet time on this one as I’m particularly sensible to the topic. If one thing I learnt of this hobby is that source quality comes ages before drivers quality. I won’t anticipate the conclusions but in a nutshell Micro iDSD Signature is a remarkable player, sporting some great and even some unique features.


Physical endowment


Infrastructure

The device is easily transportable, but nowhere near to pocketable. Not really eligible if you are looking for a walker. Good as a sitter though.


Battery

Micro iDSD Signature exclusively works from its internal battery, it never gets power from the USB VBUS bit.

This is good from the sound performances standpoint as while playing it relies solely on local battery generated power which is apriori less electrically dirty compared to the power coming from an uncontrolled host, or from a budget power supply unit.

On the other hand this means Micro iDSD Signature needs to be charged, and this happens from a separate USB port, a USB-C one.

The battery charging circuit is compatible with quick chargers and protected vs excessive voltage. Based on a direct interview I had with iFi tech people the maximum exploited charging amperage is 1.5A – whatever above that will not harm the unit, but will be wasted.

Next to the USB-C port dedicated to battery charging there is a tiny color-phased led: that is the sole visual indication informing us about the battery charge level.

Battery capacity is above decent. iFi declares circa 12h on Eco mode, 9h on Normal mode depending on load and volume of course. My experience matches such values, give or take.

Lastly, micro iDSD Signature has no “sleep” feature: if you leave it on while not playing batteries will go on discharging.


Inputs

Micro iDSD Signature has no analog input. So unlike its predecessor Micro iDSD Black Label it can not be used as a standalone amplifier. Which is a pity, as the amp section is not bad at all as you’ll read later.

Two digital input are available: USB and S/PDIF.

The S/PDIF port accepts either 3.5mm coax or Tosink optical connections (a Toslink mini-plug adapter is supplied), but exclusively supports PCM only up to 192KHz sample rates.

The USB port is iFi’s “usual” recessed-USB-A-male connector (same as on Nano iDSD BL, Hip Dac, etc). Depending on firmware, up to PCM 768KHz / DSD512, in addition to MQA, are supported through this channel.

As mentioned above, the USB-A port is for data only and no power charging happens from this end. Which is good, as VBUS is usually a major source of electrical noise and therefore distortion.

The bad news though is that Micro iDSD Signature includes only limited, anyhow insufficient, “USB filtering” features. And it shows.

Ifi’s description talks about an “intelligent memory buffer” relying on a high precision internal clock. The presence of a (legacy) iPurifier circuitry inside is also in the specs. That said, I tested Micro iDSD Signature both natively plugged onto my PC and plugged through my Nano iUSB3.0 conditioner – and the output quality difference is significant. USB dejitter inside Micro iDSD Signature is sadly not something to write home about and this is bad when looking at its DAC module quality (more on this later) which does deserve a much better effort on this front.

My assessment has been conducted using Nano iUSB3.0 upstream. For your curiosity, here you can find some info on Nano iUSB3.0 and the general digital stream conditioning topic.


Outputs

Micro iDSD Signature offers both 6.3mm and 4.4mm phone analog output, and 2xRCA line output.

The Line output works on fixed parameters: > 2V voltage, < 240 Ohm impedance, > 117dB (A) are the key declared values.

Phone outputs come with some very interesting modulation features such as the option to select 3 different amplification power levels (labelled Eco, Normal and Turbo mode), and engaging a built-in iEMatch circuit. Much more on these down below, in the Amp module section.

Very appealing is also the adoption of a full-analog volume control, technologically offering better quality compared to a (cheaper) digital volume modulation option.

Finally, Micro iDSD Signature offers 2 switchable sound shaping options called XBass+ and 3D+, which I again I will cover in better detail later below.

Power mode selection, iEMatch circuit, Xbass+ and 3D+ only apply to headphone outputs. All of these are totally uneffective on Line output.

Differently to what happens on most similar devices, Micro iDSD Signature provide exactly the same power levels either on its 6.3mm or on its 4.4mm phone out ports.

This is evidently not unrelated to the fact that both ports are actually linked to the same “S-Balanced” internal circuit.

S-Balanced is the name of some iFi’s technology, short for “Single-ended compatible Balanced”. iFi also adopts it inside Pro iCAN, xCAN, xDSD and Nano iDSD Black Label. Refer to their own whitepaper for a nice technical description.

Also, if you are not familiar with what TRS / TRRS means, this may help.

Simply put, a cabling scheme is put in place behind both phone ports on Micro iDSD Signature:

  • When plugging TRS plugs – the port delivers “normal” single-ended output. All single ended drivers on the market will seemlessly work in there. In addition to that, thanks to how internal cabling is designed, they will also get 50% reduced crosstalk compared to what they would get from an ordinary single-edend port – for free.
  • When plugging TRRS plugs – the port delivers full “balanced-ended” output to balanced-cabled drivers, resulting in quite apparently cleaner and more dynamic sound.

I’m a strong supporter of the S-Balanced concept. So much so that I think iFi should dedicate more attention to it and better “close the loop” in terms of offering their users all the tools needed to fully exploit their technology. Let me explain.

For how hard I tried, I never found a 6.3 TRRS M connector available for purchase. Nor I would know where to buy a 4.4mm TRRS M to 3.5mm TRS F adapter, for that matter. iFi themselves do not offer any of such adapters on their options catalogue – and this is really odd to say the least.

Long story short, while and right because I understand the value of the S-Balanced option included on iFi Nano iDSD Black Label much better – where no 4.4mm nor 2.5mm native-balanced port is available – in the Micro iDSD Signature case I think no user possibly can take advantage of the connectivity flexibility opportunity, which will rest as an unexploited value.

So in daily practice the user will expoit Micro iDSD Signature’s balanced-ended and single-ended phone outputs “the old way”, “as if” they were a single-ended-only port (6.3) and a balanced-ended-only port (4.4).

Unlike what happens on most competition the user will get equal power from either port, and very similar cleannes too (the S-Balanced circuit behind Micro iDSD Signature’s 6.3 port will deliver uncommonly low crosstalk to single-ended loads as per design – you did read the whitepaper didnt you?).


The DAC module


Firmware options

Like most if not all other iFi DAC devices, Micro iDSD Signature can run a range of firmware variants, each offering specific features or optimisations. I find iFi’s approach of leaving the user free to choose amongst such different options a very welcome added value.

Firmware packages and the apps required to flash them are freely available on iFi’s web site, here. The flashing process is really easy and straightforward, at least on Windows platform (did not try on Mac).

The 3 significant versions to choose from for Micro iDSD Signature are:

SupportsDoes not support
7.0MQA, DSD up to 256 on Windows, 128 on Mac, PCM up to 384KHzDSD 512, PCM 768 KHz
7.0ciFi’s proprietary GTO filter, MQA, DSD up to 256 on Windows, 128 on Mac, PCM up to 384KHzDSD 512, PCM 768 KHz, GTO on S/PDIF input
7.2DSD up to 512 on Windows, PCM up to 768KHzMQA
I’m not much into DSD (I’ll explain why in a later article maybe) and I don’t de facto currently own nor plan to own music files sampled above 192KHz, so the two options which get my attention are 7.0 and 7.0c.

Their fundamental difference is one only but a significant one at that: with 7.0c iFi’s own GTO (Gibbs Transient Optimised) filter replaces Burr Brown’s native reconstruction filters.

I strongly recommend you read iFi’s whitepaper about why and how this may be technically desireable, or not.

Did you read the paper? C’mon do it! Seriously…

As you’ve seen the paper focuses on throughly illustrating GTO’s output features while leaving another important aspect in the background: with 7.0c Micro iDSD Signature will systematically upsample all digital input coming from the USB port up to 32 bit / 384KHz resolution prior to feeding the DAC chips. For what I seem to have understood this is fundamentally required for the GTO filter itself to work as intended.

It’s at this point worth noting (or remembering, for those who follow my articles) that I already experienced iFi’s GTO implementation in conjunction with Micro iDSD Signature’s smaller sibling, the Nano iDSD Black Label.

My full take on that is here, but in short: on Nano iDSD BL the GTO option “sounds worse” than the native ones – for my tastes at least. My suspect is in that case the upsampling effort ended up not adequately turned into higher sound quality delivery due to inherent dac bandwidth limitations.


DAC performances

Micro iDSD Signature on firmware 7.0 offers very nice DAC performances.

Range is superbly extended, sub-bass is fully and correctly rendered, bass is bodied and especially phenomenally controlled, mids are present without exaggerations and trebles are powerful and vivid.

Particularly significant are cleanness, note separation, imaging and layering.

Directly compared to my reference DAC which is Apogee Groove (my take here), Micro iDSD Signature on firmware 7.0 has a deeper lowend extension on one side, a less extended treble span on the opposite side. Tonally it comes accross even more controlled than Groove on the bass (up to delivering a “leaner” flavour there), very similar on the mids and trebles. Draws on 3D space very, very well, although still not precisely at Groove level. On space rendering alone, Micro iDSD Signature is the single DAC that comes closer to Groove that I heard as of yet, and that’s saying quite something.

A very evident feature of Micro iDSD Signature DAC which is worth underlining is tight transients.

The “Bit Perfect” option is very tight. All notes are snappy, razor cut. Switching onto Minimum Phase or Standard transients get a tad more relaxed, less “dry”, yet the general impact stays way into “analythical” territory, especially when compared to a more “musical” alternative e.g. Apogee Groove.

In terms of transients rendering Micro iDSD Signature is actually more on Chord Mojo ballpark – for those who have experience with that. Mojo stays a bit ahead of Micro iDSD Signature on its unique capacity to close the gap between front and back instruments, however Micro iDSD Signature provides quite evidently better results in terms of extension, lack of coloration, and detail, and seriously beats Mojo on space rendering (which never was Mojo’s specialty, there’s that…).

With firmware 7.0c Micro iDSD Signature will upsample all digital traffic incoming from the USB line prior to passing it to its DAC chips.

While this does not produce any “dramatic” difference when the original samples come at an already high resolution (96, 176 or 192 KHz), an evident improvement is audible when 44.1 or 48KHz material is being supplied, and especially so of course if the track mastering is good.

The improvement is of course mainly on spatial reconstruction, size shaping and imaging.

Pulling back the comparison vs Apogee Groove, firmware 7.0c comes out as a major point of advantage for Micro iDSD Signature. Both DACs show great mastery beyond the 40KHz mark (where most of the information on space, reverberations etc come from) but that only is applicable if there actually is some digital data in that region to be decoded. On native 96KHz++ material the two DACs compete head-to-head. On lower sample rate material Micro iDSD Signature offers a built-in, automatic and very well implemented (!) upsampling option, while Groove has to rely on the same happening on the host (if ever.

Another interesting note: Micro iDSD Signature is very much able to exploit the GTO upsampling and convert it into a tangible benefit to the user when busy with sub-hires music at the very least, while the same does not happen on Nano iDSD Black Label. Why? I don’t know. I suspect this is either because the GTO algorithm is better implemented on fw 7.0c (usable on Micro iDSD Signature) vs fw 5.3c (usable on Nano iDSD BL), or because Nano’s lower-tier DAC section is unable to exploit the opportunity. Or both.

Another very important note to make about GTO is that it renders transients even tighter compared to the already tight Bit Perfect option on non-GTO 7.0 package. And, there’s no escape: when 7.0c is installed only one filter is available – no Minimum Phase or Standard alternatives are attainable. You better like it as is…

And simply put, I don’t. I find it excessive. I do appreciate of course clarity and cleanness, and precise rendering of each note – it’s a matter of “levels”. This is of course totally subjective. I have friends considering GTO’s reconstruction “supremely natural”. I’m afraid I can’t anticipate which one you will prefer.

One dufitul last note: I don’t use MQA, so I did not try / test Micro iDSD Signature’s proficiency on that. Not big loss for you as due to what I just wrote I honestly haven’t got any decent experience / opinion to offer on this topic, other than the trivial comments you can easily find everywhere and don’t certainly need me to paste here.

Summarising: Micro iDSD Signature offers very, very good DAC performances. Imaging and spatial drawing in particular are nothing short of spectacular. GTO firmware offers automatic well-executed upscaling to sub-hires audio tracks. Transients are rendered from quite to very tightly, which more musical-sounding presentation lovers might not like.


The AMP module

As I quickly pointed out up above, Micro iDSD Signature offers some very interesting features when it comes to its internal amp section.

Firstly, its internal S-balanced architecture is equally available on both the 6.3 and 4.4 port, although for the reasons explained above in the real world scenario you can bet the two ports will be used as if the former was single-ended only, and the latter balanced-ended only. Too bad.

Secondly, and obviously related to the previous point, both ports provide the same output power levels – so choosing either is not a matter of power delivery, rather of convenience, and of a little cleaner output (better xtalk value) when a balanced connection is established on either port – so de facto on the 4.4 one for lack of avaialble 6.3 trrs connectivity options.

Finally, it allows for power level reconfiguration at the click of a switch to optimally supply high impedance cans – requiring as high voltage swings as possible – or low impedance and low sensitivity ones, like planars – requiring little voltage and very intense currents – or even IEMs. Three different “powering levels” are available, selectable with a switch on the device side, and a built-in IEMatch module is also available for added measure.

At the Normal power level – the intermediate one of the three total – Micro iDSD Signature outputs something short of 2W max power (a bit less than 1W RMS @ 32 Ohm) and 5,5V max swing. That’s already great power.

My Shure SRH1540 (46 Ohm 99dB, but much more current hungry than spec facevalues tell) are biased very satisfactorily on Normal level: bass is full while also staying very controlled, trebles are nicely sparkly – within the limits of a treble-polished driver like 1540 of course.

Indeed, switching iEMatch on makes the situation even better as it tames a further bit of the unneeded voltage swing, making bass come out futher controlled and cleaner. A real pleasure to hear. IEMatch High setting is already sufficient in this case, which is consistent with SRH1540 impedance being still significantly higher than IEMatch-H’s 2.5 Ohm output impedance.

Switching Micro iDSD Signature to Turbo is not a good choice for SRH1540 – and that’s perfectly in line with logic too. The effect of excessive voltage swing on a low impedance load like that is similar to a taxing “Super High Gain” option: dynamics get closed-in, range is compressed, highmids get glary and expecially midbass goes too bloomy.

Same situation takes place with Koss KPH30i (60 Ohm 101 dB). Best biasing is obtained from Normal power + IEMatch-High. Eco power makes them sound muddy(er). Turbo power is totally excessive, KPH30i presentation gets unnatural.

As those who follow my articles probably already know, I’m not into high impedance cans, nor into extremely power hungry planars so I won’t comment on how the Turbo option does in those cases. Suffice here to say that Turbo setting promises 10V max and a tad more than 4W max power (1.5W RMS @ 64 Ohm), not peanuts at all for a portable device and many budget desktop ones either!

On the opposite end of the spectrum, I must stand and vigorously clap hands at how iFi solved the IEM equation instead: the combined benefits of the Eco power option and the built-in IEMatch module are nothing short of spectacular.

As all technically aware audiophiles know, IEMs despise high voltage and most times high power altogether. Impedances below 32 ohms – sometimes as low as 8 Ohm or less – like those on IEMs require (require, not simply prefer) low voltage swings, which is the exact opposite of what a voltage modulation amp powerful enough to drive higher impedance headphones is designed for.

When up to driving IEMs the very first thing to do on Micro iDSD Signature is to set the power switch to Eco setting. This makes sure the maximum delivered voltage is limited to 2V, and the maximum power is 500mW on an 8 Ohm load, which is way more than 99.9% of IEMs out there requires.

All of my IEMs are in facts perfectly driven by Micro iDSD Signature, on Eco mode and – on a case by case basis – with IEMatch set to Ultra or High. Same for my final Sonorous-II (16 Ohm 105 dB) which are closedback overears electrically behaving very much like IEMs: the best setup for them is Eco, with IEMatch turned off, although Normal + IEMatch Ultra is also a strong contender.

I am Soon™ going to publish a comprehensive article about IEMatch but I guess it’s worth to synthetically recall what IEMatch is here.

In its standalone incarnation iEMatch is a device to be plugged in between an amp’s headphone port and a IEM or Headphone cable, and vulgarly said it does 3 things:

  • It “tricks” the amp into sensing a predetermined load impedance of 16Ω, regardless of the IEM/Headphone’s real (average) one.
  • On the opposite end it also “tricks” the IEM/Headphone into sensing a predetermined amp output impedance, regardless of the amp’s real one. The user can flip a switch and choose between 2.5Ω or 1Ω.
  • It attenuates – think about it as if it “sinked” – the amp’s output by a predetermined amount: -12dB when output impedance is set to 2.5Ω, and -24dB at 1Ω

Micro iDSD Signature already comes with a number of features making some of its IEMatch built-in circuitry redundant, read useless: I’m talking about very low output impedance, support for loads as low as 8 Ohm and a volume pot in the analog-domain. That said, the IEMatch module stays beneficial to 2 main purposes: further reduce output voltage swing, and eliminate sibilance on hyper-sensitive IEMs.

The former of the two benefits is especially intriguing: on a case by case basis some drivers do sound better under Eco power other sound better under Normal power with IEMatch Ultra switched on on top. And for some others… it’s hard to tell – e.g. final Sonorous-II, Tanchjim Darling, final E5000.

Mind you: from a purely technological standpoint the topic is arguable upon to say the least. Post-attenuation does come with benefits and drawbacks like, I guess, everything else in life. The information I want to convey here is not how exactly I recommend to set Micro iDSD Signature to work best with this or that IEM, rather that the device offers the flexibility to try different ways to that target.


A truly multipurpose amp – finally!

As I mentioned before, to my knowdge at least there’s no single amp implementation out there yet which is capable of feeding different impedance/sentivity drivers with equally optimal results. And to my understanding, there’s a solid technological reason for this : high impedance cans “sound better” when submitted to high voltage swings, low impedance HPs and IEMs distort in the same condition. Simple as that.

Conceptually we have 3 possibilities then:

  1. Use different amps for the various cases.
  2. Use a high voltage amp, and aposteriori cut its output voltage down. That’s where attenuators e.g. IEMatch may help.
  3. Use a sort of “configurable” amp…
Micro iDSD Signature’s amp can be reconfigured to optimally support very high impedance cans (Turbo mode) or low sensitivity cans (Normal mode) or low impedance + high sensitivity IEMs (Eco mode) offering each category its own best welcome powering profile.

When facing low impedance loads, in addition to selecting Eco power mode there may still be need to engage the built-in IEMatch module to furtherly reduce output voltage, which will benefit current delivery to particularly sensitive drivers, and/or cancel some hiss out of the most sensitive of those.

Of course a curious question as this point might be “which of the two features should I preferably use before the other: Eco power mode, apriori limitating voltage swing, or IEMatch, cutting it down aposteriori” ? I had my own opinion on that already but I asked iFi’s designers’ take on this.

With regards to Turbo/Normal/Eco modes vis-a-vis headphone matching, our AMR audio background means that we are of the opinion that while the impedance of a headphone is a factor to consider in matching, the over-arching one is actually power > sensitivity.
This is why we developed the headphone calculator which takes the power output of a headphone amplifier and compares it to the headphones to be used. The resulting volume level will give the customer the best insight into the ‘matching’. Just like a 1,000W Mark Levinson would be a poor match for high-sensitivity horns rated at 110dB sensitivity. Or a 10W 300B SET would not drive 87dB Magicos.

iFi’s headphone calculator is indeed an informative but most of all educative tool. Playing with it we can find out how wrong are common assumptions about this or that driver (IEMs or Headphones alike) requiring “high power”…

I can’t stress enough how brilliant I find iFi’s choice to equip Micro iDSD Signature with what it takes to allow the user to substantially change its amping behaviour to cope with the dramatically diversified nature of those drivers out there. A really, really welcome idea, and a unique one in the mid-tier segment this device partakes into at the very least, but to my knowledge in the one above too.


Sound shaping addons

Similar to what is also offered on other iFi devices, Micro iDSD Signature’s amp section features two optional circuits providing bass enhancement and imaging improvement at the flick of a switch.

Both features are according to iFi’s documentation entirely implemented in the analog domain. No DSPs are involved which promises the minimal impact on sound quality of course.

“XBass+” behaves like what an EQ expert would call a low shelf positive filter. By ear I would say it pushes lows up by 2dB-ish from 100Hz down. Very personally speaking, I don’t like these types of options in principle – irregardless of their implementation quality that is – my fundamental position being: if I want more bass than the one delivered by the driver I’m using right now… I swap on a different driver. In the special Micro iDSD Signature case, XBass+ may be actually welcome to “compensate” the device super-lean bass presentation, especially as delivered by the GTO filter (fw 7.0c).

“3D+” is a “crossfeed filter”, i.e. a function that puts “some” of the right channel output into the left one and viceversa, simulating on headphones what happens when listening to loudspeakers. Within its limits (it’s not parametric, configurable etc – just a mere on/off) and situationality (effects are totally evident on some tracks, minimal on others) the trick is really nice, and I used it quite often. My main application case are those original jazz masters from the 60ies where mixing tended to be executed by hard panning each instrument on a single channel only: 3D+ sounds almost magical in those cases.


Conclusions and evaluations

Well, I’m certainly not known for generosity when it comes to assign good scores. This time I must say that from the technical standpoint Micro iDSD Signature deserves a very high remark.

DAC reconstruction quality on high-res lossless material is at the absolute top I found below 1K$ and possibly above. The sole other devices who can play an even match with Micro iDSD Signature on this part are Apogee Groove and Questyle QP1R, all the rest being a full class below at the very least. My experience is not oceanwide, so there may be others of course, but still....

Not only: adopting firmware 7.0c Micro iDSD Signature automatically upsamples all USB input thereby granting a significant share of the same quality to sub-highres tracks. Upsampling is not black art, it is very possible to implement that on the host, and feed competing DACs with the same improved input, and obtain improved output from those too – but it must be done, and done right, which is an extra burden and cost, while Micro iDSD Signature does it “out of the box”, and does it right too, and this is a major value on my scorebook.

Micro iDSD Signature’s DAC is so good that a no brainer rec is to exploit the Line Out option and interconnect into a serious quality desktop amp any time that’s possible (nothing short of a Jotunheim-2 at the very least will make Micro iDSD Signature’s DAC decent justice), but mobile DAC+AMP standalone operation will not disfigure at all when compared to no matter which top alternative device in its same price class.

Always talking about standalone mobile features, Micro iDSD Signature’s ability to reconfigure its amping section on the fly to optimally cope with IEMs, or low impedance cans, or high impedance hps, or “nasty” planars is totally brilliant, and deserves – that alone – a standing ovation for the idea, and the implementation quality too.

As always where there’s light there’s shadow too.
The DAC section is so good that the lack of adequate built-in USB dejitter becomes very evident, and frankly I find it almost disappointing.
On an even more subjective level, all filters in general and the GTO filter in particular deliver extremely tight transients – some may find them “more natural”, I find the opposite.

Last but not least, the price – and the value.
At € 699,00 EU list price Micro iDSD Signature is not an inexpensive device.
And please add another € 50 at the very least (iSilencer) or better another € 150 (iPurifier3) to add some improved USB cleansing.

Is it worth it?

Well, evaluating it in terms of a truly mobile (if not pocketable) device, not relying on host batteries, offering top class DAC competence, and truly capable to optimally bias anything, from the “easiest” IEM up to the “nastiest” planar overear well… Micro iDSD Signature is an easy win.

Such consideration does not make its price tag cheaper of course, but finding another battery driven device with similar output quality at a significantly lower price – at least to my knowledge – is today a hard task.

Totally different is of course the perspective if we plan a mainly static, “desktop” application. In such case Micro iDSD Signature stays a very significant device, but the price of its unexploited portions would make its convenience score poorer.


Disclaimers

This Micro iDSD Signature device has been provided as a temporary loaner unit by iFi for the sole purpose of my assessment.
This article is also published here.
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JasonLucas

New Head-Fier
Desktop THX sound in a portable amp
Pros: Desktop THX sound in a portable amp
( it’s not a THX amplifier but sounds like a great one )
Extremely powerful
Drives everything I have even fostex full size planars
Full body smooth neutral sound signature
Cons: 4 hours battery life at full power ( is this really a con though?) that’s damn loud
Battery gauge hard to judge
Pop on and off noise with dial
Ifi micro signature

Very neutral and flat sound signature (especially compared to zen can and hip dac ) reminds me of a good THX amp ( not weak on bass or sterile ) does not color sound at all that I could hear
Good technicalities, dynamics and punch
Excellent build quality and looks
6.3 and 4.4 both offer full power , balanced or single ended
( don’t have to use balanced cable )

4,100 mW output at 16 Ω
Balanced output through 4.4 mm jack 6.3 offers single ended but same exact power output
Transportable vs Portable ( it is kinda big and heavy, fits in bag and on a desk but not in pocket really )

500 mW (8 Ω, Eco mode)
1,900 mW (16 Ω, Normal mode)
4, mW (16 Ω, Turbo mode)
1,560 mW (64 Ω, Turbo mode)
166 mW (600 Ω, Turbo mode
Output impedance is less than 1 ohm with iem match disabled
Supports MQA out of the box
Front panel Status Led has 7 different colors that will light up.
Magenta is MQA, and red indicates DSD512.
The volume dial also acts as an on/off switch. Feels great and is responsive, again quality.

Front panel also includes XBass and 3D mode. Along with a built-in IEMatch,on the side which allows sensitive IEMs to be used without hiss and 3 power modes. ( ECO, NORMAL, TURBO)
These offer more power and thus drain the battery at corresponding levels. A digital filter switch is also included, but this has no function with the current firmware.
3D Mode tends to brighten the sound to my ears and could be a use on certain pairs to enhance treble.
Xbass (as always with ifi) is the best bass boost I’ve ever heard but I do not use it most of the time ( works great on p1 and heart mirror )

On the back of the Signature is a S/PDIF 3.5mm coaxial input for the Toslink mini-plug connection. RCA output and a USB 3.0 type A input port. Works with android and IOS with the correct cables

Included in box
6,35mm jack adapter, USB OTG cable, adapter OTG – USB-B, two rubber bands, optical adapter, RCA cables, soft pouch, and 10cm USB-C cable

4-10 hours of battery life depending on usage, power level and volume used.

Cons

Audible pop noise when turning on and off ( didn’t have to be necessary imo )
Is kinda hard to tell what level the battery is at.
Its kinda expensive but replaces most my desktop amps.

This is a one of a kind on the market, nothing else like it.
It’s awesome.

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The last of the old-style iFi Micro DAC/amps makes for fun listening.
Pros: Low hiss yet lots of power. Very engaging sound. Feature set. 6.3mm (1/4") output has the same power as the 4.4mm.
Cons: Power switch/volume combo limits volume setting range and adds channel imbalance. Size. Odd input set-up.

iFi sent me the Micro iDSD Signature, without any prerequisites, for review.

I've long been curious about the Black Label series of portable iFi DAC/amps, given their popularity. Quite a few people have wanted me to review them as well, so when iFi offered me the Micro iDSD Signature, the last, limited edition release of the range, I jumped on the chance.

Hardware

iFi Micro iDSD Signature IMG_4627_.jpg


Externally, the iDSD Signature comes across more as "transportable" than portable, being larger than even Chord's Mojo/Poly combination. Adding to this is the range of inputs and outputs, the front 6.3mm (1/4") socket being the most prominent on the front, and the RCA jacks likewise on the back.

With the Signature, a 4.4mm Pentaconn port is added. While the iDSD Signature doesn't use a balanced circuit internally, this means that you don't need to use the 4.4mm socket to get full power out of the device. The 6.3mm socket will do just fine for that.

iFi Micro iDSD Signature IMG_4626_.jpg


Except for the USB-C power socket on the side, iFi has yet to move away from their strange, if cleverly logical use of a full-size USB-A plug as the main input. While initially odd, it makes sense when you see the included USB 3 extension cable in the box, chosen for its better shielding (the input is only USB 2).

Unlike the previous Black Label version, the 3.5mm input on the front is no longer available. Only digital input is possible.

Hiby R6 iFi Micro iDSD SignatureIMG_4925_.jpg


If you decided to do an old-school "stack" of phone or DAP with the iDSD Signature, then all you need is a USB-C or Lightning to USB-A socket adaptor, both readily available. Not to mention, a USB-A plug-socket is more reliable than a USB-C one, in my experience.

If USB is not preferred, a combo 3.5mm S/PDIF and mini-optical jack is included, though the high-res support is somewhat more limited with these.

Speaking of which, the highest input resolutions of DSD512 and PCM768 are only available if you downgrade the firmware to 5.2, and eliminate MQA. Given that these are unicorn formats, and up-sampling to that level will add no benefit above the DSD256 and PCM384 limit with the stock firmware, the point is rather moot.

Features

One of the keys to iFi's popularity has been their inclusion of features such as the XBass and 3D modes in their products. Along with a built-in IEMatch, allowing sensitive IEMs to be used without hiss, and 3 power modes. A digital filter switch is also included, but this has no function with the current firmware, and, like the ultra-high-res input, only works if you downgrade the firmware to the non-MQA version.

The XBass feature adds a nice, but not excessive amount of bass, filling in things nicely with headphones that are more neutral in tuning, such as the Final D8000 Pro, which I used with the iDSD Signature.

The 3D mode, on the contrary, has the perceptive effect of brightening the music, even though it uses crossfade and doesn't change the frequency response, making it sound more open. Combined, you get something of a v-shaped sound, which can be good if you're like me and listen to a wide variety of music, and tweaking the sound in this way can make genres that are less compatible with one's headphones more enjoyable.

iFi Micro iDSD Signature IMG_4951_.jpg


The three gain modes, labelled Eco, Normal and Turbo, allow one to trade battery life for power, or provide a better range of volume adjustment for one's headphones or IEMs.

Of that, the volume control is one of the negatives of the iDSD Signature. Including the power switch, it has serious channel imbalance until you get to about 10 o'clock on the dial, leaving little over 180 degrees of movement for volume adjustment, a fair bit less than if a separate power switch had been used.

The other, main negative, is a lack of any indication of battery level. While it's readily possible to get up to 8 hours, or possibly more, of listening time, not knowing when one is about to run out of battery can be a bit frustrating. The only indication of anything power-related is a light showing that the unit is charging next to the power input USB port.

In Use

I usually start with IEMs when testing a portable device, and so I brought out the 2020 Campfire Andromedas to do my regular hiss test. Even with the unit at full volume in Turbo mode with the IEMatch off, the blood running through my head was louder than the minute amount of hiss that was audible, and the IEMatch cut even that! A great pass there.

Powering the Andromedas, while a couple of Ohms output impedance doesn't usually change their sound signature, the IEMatch seemed to drop the bass a bit in the first "High" mode, with it coming back more somewhat in "Ultra" mode.

This was mildly regrettable, as there isn't much volume range to begin with in Eco mode, and the IEMatch allowed the volume knob to be adjusted to a more useful position with the Andromedas.

Listening impressions

I had the Neo iDSD here at the same time, which provided an interesting, and quite dramatic contrast.. Unlike the Neo iDSD, the iDSD Signature is quite warm and engaging, with a stronger sense of bass presence than even the Chord Mojo, which is slightly on the "warm" side of things. While not providing quite the sense of sharp relief that the Mojo does with good acoustic recordings, the iDSD Signature gives the sound more body, even as a DAC, and makes for very engaging listening.

Full-sized headphone drive is very good for a portable device, with a generally clear and punchy sound, even with the high-end planars I have here, such as the Final D8000 Pro and Meze Empyrean. The results aren't as good as using a dedicated headphone amp, such as the Schiit Jotunheim, which is on another level altogether. However, sans comparisons, the enjoyment factor is very high with the iDSD Signature.

In the world of portable audio, there are always sacrifices at any price point. Want a conveniently device? You'll sacrifice power and/or battery life. Want functionality? Fidelity may be the sacrifice instead. With the iDSD Signature you get plenty of headphone-driving power and work-day battery life, but you need a transport, such as a phone, DAP or computer to use with it, and it's not readily pocketable.

Likewise, rather than the sharper fidelity and wireless convenience of a Mojo/Poly combination, you get an optional bass boost and 3D mode. This is where the iDSD Signature succeeds, in making the music enjoyable, even if not delivering absolutely the most fidelity available as you can get from something like a Hugo 2 or desktop rig.

The D8000 Pro is tuned towards "neutral", which can make it less entertaining to listen to some music with. Yet, engaging the XBass brings a pleasant boost when some more warmth benefits it, giving the headphones a character more like the Empyreans.

Likewise, I tried the iDSD Signature as a DAC into the ALO Audio Studio Six and Audio-gd Master 9 with good results, the sense of warmth and engagement coming through strongly, adding a sense of joy in combination with the better amplification.

Conclusion

I've enjoyed my experience with the iFi iDSD Signature. I understand now why the Black Label version was so popular. Providing plenty of power for full-sized headphones, yet almost complete silence even with sensitive IEMs, the iFi Nano iDSD Signature has a punchy, warm and engaging sound that makes it a joy to listen with, and options to bring out a bit more entertainment from the music.

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Last edited:
Currawong
Currawong
@Dixter Whether it is balanced or not has no bearing on the power output. If anything, it would be worse in respect to the single-ended output, which would then be lower power, or the device more expensive so that both a balanced and dedicated single-ended circuit could be included.
B
bnupy
Regarding the No battery level indicator.
I think the ifi documentation says the light near the usb c connector. Flashes white: near full charge, green: in between, and red for low battery.
Currawong
Currawong
Fixed that mistake, thanks. I hadn't noticed it, since it was tiny.

rev92

100+ Head-Fier
iFi iDSD Signature
Pros: That color
Good build quality
Very neutral and flat tonality
Good technicalities
Features
It's iFi Audio
POWAH
Cons: Might be boring for some
Lacks juiciness
dscf5555.jpg


iFi iDSD Signature is the newest transportable DAC made by iFi. It pushes 4W of power into the headphone output, decodes MQA, and it is priced at 649$.

Sound quality for the price
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Rating: 8.5 out of 10.

Build quality
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Rating: 8.5 out of 10.

Value
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Rating: 8.5 out of 10.


Packaging

Long list, but short USB-C cable.

iDSD Signature, same as the iDSD Neo, has refreshed design of the box. It is grey with the Signature’s photo on the front.
Inside you will find a long list of useful accessories:
6,35mm jack adapter, USB OTG cable, adapter OTG – USB-B, two rubber bands, optical adapter, RCA cables, soft pouch, and 10cm USB-C cable.
As always, it is packed inside in smaller cardboard boxes.

Build quality

This new color is gorgeous.

iFi again shows how it cares about the details and build quality, but there’s one thing that could be better. It is almost the same as iDSD Micro Black Label but in the new navy blue color, which looks definitely better in real than on the renders. iFi also removed some switches on the device, but that doesn’t change much at all.

Beginning with the front, you will find the 6,35mm jack output and the 4,4mm one. iFi cut the 3,5mm analog input. The next thing is a pretty huge LED indicator that shows the quality of the files. It is matte and quite dark, but I don’t have any problems recognizing the color in the daylight. Thanks to the low brightness, it also doesn’t light up the whole room during nighttime. Going further, two switches – XBass mode and 3D. I’ll talk about them more in the next paragraph, here I can say they’re delicately too small for me, sometimes I have to try a few times to change their position. The last thing placed on the front is the potentiometer, which also turns on the iDSD Signature. It isn’t the best I’ve ever used. After turning for about 30 degrees, it starts playing, but with disbalance – only the left channel is working. I have to rotate it for another 10 degrees for the right channel to begin working. After that, it is working linear, but the first step isn’t encouraging.

On the right side, there is only a USB-C connector for charging. It is placed pretty deep, I have problems with some cables to work correctly, and the attached cable is too short to charge it comfortably.
The left side is equipped with three sliders, the same you can find on iDSD Micro BL – power mode, digital filter, and the iEMatch.
On the rear there are placed USB Type-A, SPDIF input, and RCA outputs.

dscf5495.jpg
I’m missing the 3,5mm jack input.

Functionality

dscf5565.jpg
Those logos of used technologies are a nice addition.

iFi is a company that loves to put new technology into its devices, and it isn’t different this time.
As the first, but an obvious thing, MQA decoding for Tidal Master Quality files. The second thing that is definitely worth to be mentioned is S-Balanced output circuitry. It means that Signature delivers improved sound quality, usually reserved only for balanced output, within both outputs, even the single-ended one. It cuts crosstalk and distortions in half based on the iFi’s words.
The functionality behind the two front switches, which were also in iDSD Micro BL, was hardly improved. XBass function works way better than ever. It isn’t only a loudness. It truly warms the whole sound, without any echo feeling.
The 3D function is also useful in the music when in the iDSD Micro BL, I would use that only for games or movies. It doesn’t work such strikingly in iDSD Signature, but it is way more accurate. It is hard to get used to it in one minute, but after some time, in my case, after about one hour, it began being useful also in gaming.
On the left side, you can see three switches that work in the same way as in iDSD Micro BL. Power Mode, which is similar to the gain, iEMatch to use the Signature with low impedance IEMs, and the filter – Bit-Perfect, Minimal Phase, and Standard. It is basically from the sharpest to the most natural.
Battery life is also great at about 12 hours.

Sound

Maybe the color is more saturated, but the sound is flatter.

It is time for the essential part of every audio device, the sound. iFi iDSD Signature is a pretty nice upgrade compared to iDSD BL. It has the same sound signature, so it is natural to neutral (depends on the filter), wide soundstage, great holography, but it is different in one thing. iDSD Micro BL isn’t imposing much from itself, and it lets your cans sound just how they are meant to. The new Signature came up a little less saturated, more technical, keeping the headphone of choice a little bit tempered down.

The bass isn’t the party king. It isn’t much saturated, but really flexible. It doesn’t matter if you prefer the speedy bass or the sloppy one, iFi provides both of them. If you prefer the juicy bass just turn on the xBass option, it will be closer to the Neo bass, but with extra weight.
Lows aren’t as highly textured as I like, but I love how they disappear after the strike—just boom and silence, but only when it has to. In the other situation, it can be slower but never gets muddy. It all depends on the mix and the song. In two words, this bass is clear, tight, speedy, and very flexible.

The midrange has delicately more life than the bass, but it isn’t on the iDSD Neo level. It is pretty smooth with female voices and provides a lot of air with excellent separation, which can be really surprising. The midrange doesn’t have any charming feeling, more like the natural flat. Lower vocals are nicely textured, without dryness. For me, it is the best part to get focused on. Even the awful recordings of Rammstein provides fantastic impressions after listening to the Till Lindemann voice.
As I mentioned above, the Signature doesn’t impose almost anything, but it doesn’t get way too technical and transparent.

It’s just very detailed, very accurate, and correct.

dscf5481.jpg
I think the “Signature” is a wrong name for the new iDSD as long as it doesn’t really have its own sound signature.

The treble is spot on, again. Not sharp, not smooth, just natural with lovely sparkles and click. All wind instruments, drum plates, or even some triangles have a full body. There’s no feeling of emptiness at any point. Click is awesome in the calm, slow songs where it behaves like the bass. Clicks and disappears in the black background.
All the sparkles are pretty calm, without any chance to sibilance.
My favorite song for the treble last time is “Pristine” by Snail Mail and it sounds wonderful also here. Listening to this pretty bright song, with pretty bright Craft Ears Four doesn’t cause pain, it pleases my ears for long hours.

The soundstage is very similar to the Micro BL overall but is broader and more profound. Also, the height is way better, it can go way higher and lower compared to iDSD Micro BL. The Signature’s soundstage is definite, without any false markings around. It doesn’t fly around with many sound sources changing their place to make the listener immerse himself in the performance. All sound sources are holding their positions, which is also great, just different.

As I mentioned in the “Technical” paragraph, the 3D function is great in gaming, but you have to get used to it. The iDSD Signature didn’t trick me even once, letting me play peacefully with a trusted sound source.

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Different products, different playstyles.

Short comparison to the iDSD Neo
iFi iDSD Neo and iFi iDSD Signature are absolutely different devices.
The newest stationary iFi DAC provides a lot more fun, saturation, and it is vibrant. The iDSD Signature is more technical and flat. The Signature has more body in some situations, with heavier sound overall. Neo has a more innocent playstyle. It is like comparing the strict father and the one that prefers a stress-free upbringing.
The soundstage is similar in terms of width and depth, but as I mentioned above. The Signature is more spot-on when the Neo gives a lot of magic, and it just swims around.
I’ll go once again with a comparison, Signature is like the F1 race, where everything has to be in place, and the Neo is like free-roam with friends at night, where you can ride how you like to.

Summary

Changes aren’t big, but it is a fantastic device.

The iFi iDSD Signature is a great successor of the iDSD Micro Black Label, but it isn’t a revolution. It provides better features, micro details, and the soundstage but overall doesn’t kill its predecessor. It is a totally different device compared to the iDSD Neo. Still, it is definitely a great refreshment that provides very high SQ with flattened natural sound signature, wide, high, and profound soundstage, but without much juiciness and vibrance. It isn’t a sound signature for everybody, but it is great if you’re looking for a flat sounding device.



Gear used during this review for the sake of comparison and as an accompanying equipment:
  • Headphones – Philips Fidelio X2HR, Kennerton Odin, Vision Ears EVE2020, Audeze LCD-3, Bqeyz Spring 2, Craft Ears Four, Hifiman HE400i 2020,
  • Sources– Topping DX7 Pro, SMSL M300+SP200, Chord Mojo, iFi iDSD Neo, Topping DX3 Pro, EarMen TR-Amp
rev92
rev92
Hi Richard! Thank you!

This words are actually from the other review above mine, so I dunno, sorry :L3000:
Richard Wray
Richard Wray
Ah, sorry. I put it in the wrong line. Your review rocked too :)
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rev92
rev92
Thank you! :)
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