Setup, Customization, and Performance

Setup

I suspect most readers of this review will be using the iFi micro iDSD Signature as primarily a USB DAC for input and headphones on the front for output, but I still decided to see whether all the ports on the back are usable if you plug them all in concurrently. Some larger units, such as the recently reviewed YULONG Aurora, struggled with this, so I was pleased to see no such issues here. The provided USB cable is almost a must to have unless you get another compatible adapter, and the bonus with this cable is you can also use it with the shorter Type-C cable to charge the internal 4800 mAh Li-ion battery as seen above. Charging times are on the order of 3-12 hours depending on the input source, with the micro iDSD Signature taking a 5 V/1.5 A power source. Likewise, battery life is heavily contingent on the power draw from the device, with 6/9/12 hours rated from iFi, depending on whether the device is in Turbo/Normal/Eco modes respectively. There is a battery indicator LED alongside the charging port that goes from white (>75% charge) to green when between 25-75%, and finally red from 10-25%. It will flash red under 10%, and continue to flash while charging too.

Another thing to point out is the volume knob needs to be turned a good amount before it clicks on, meaning the actual range of volume control is less than you might think. Thankfully the fully analog nature of the wheel combined with the various operating modes results in plenty of granular control overall. The indicator LED on the front turns green when first turned on, then flashes yellow in the absence of any input. It then remains green for PCM 44/48/88/96 kHz playback, yellow for PCM 176/192/352/384 kHz, white for PCM 768 kHz, cyan for DSD64/DSD128, blue for DSD256, red for DSD512, and finally magenta for MQA playback. That last part is also why you will notice the iFi micro iDSD Signature comes with a pre-installed firmware v5.30 that is optimized for MQA playback and is "limited" elsewhere, in that it handles up to PCM384/DSD256 playback. If you don't care about MQA like me and wish to make the most of the device in case of some spectacular sources you might have, then you should find and install firmware version 5.20, optimized to run PCM768/DSD512 (non-MQA) found here.


Using the micro iDSD Signature with Windows 10 or 11 doesn't require any additional drivers, with Windows recognizing the device automatically. We see that the default firmware provides PCM playback options up to 32-bit, 384 kHz. The integrated USB encoder microcontroller comes in handy here, and all your favorite players will recognize the device in WASAPI (Windows Audio Session API) mode accordingly. There should be equivalent drivers pre-configured in newer macOS builds too, but I am not familiar enough to speak on this front.


If you have a device that doesn't accept UAC 2.0, or even if you simply want to try other options, then the iFi USB audio device drivers will be of interest to you. You can find the installer on this page where you will be prompted to enter the device's serial number, found on the bottom via the QR code. The latest version at the time of testing was v5.12.0. Installation is trivial as seen above, and these drivers now allow you to make the most of the iFi micro iDSD Signature within the Windows OS.



What it then does is create a new output device in Windows, also providing access to the iFi USB Audio Device Control Panel. Just be sure to set the format to 24-bit and choose the ASIO (Audio Stream Input/Output) buffer size that suits your latency requirements—that's about it. With that done, go to your media player of choice. I demonstrated above with JRiver again and set the audio player to the same output. At this point, you can implement further tweaks, but those are player dependent. These drivers also provide 16- and 24-bit playback support, and you will have to change the device firmware for PCM 784 kHz/DSD512 playback as mentioned before.

Audio Performance

The RCA line output is a cool implementation on the iFi micro iDSD Signature, indeed I used it a couple of times to see how the Burr-Brown DACs fared by themselves. But the vast majority of end users would no doubt purchase this for the headphones outputs where there's a lot of power to play with. Given the portable nature of the device, I figured it'd also make an excellent combination with a portable full-size planar magnetic set of headphones too in the form of the Meze Liric which were driven extremely easily. After all, the balanced 4.4 mm output can provide >1.56 W of continuous power @64 Ω (bursts of 4.1 W possible) in Turbo mode! This ends up being more power than a lot of expensive standalone headphone amplifiers can do, so that's saying something. Indeed, there are far more power-hungry headphones which can benefit more from the power output here, although I ended up mostly using the Normal (>100 mW @300 Ω; 950 mW @32 Ω) and Eco (250 mW @16 Ω) modes, with lower power output but more battery life. Indeed, those modes are perfectly suitable for the vast majority of dynamic and planar magnetic driver headphones on the market! The single-ended output would push less power though, so I recommend trying there with the lowest volume and power mode settings, going up only as needed. An output impedance of under 1 Ω even before iEMatch gets in the picture is great, and iFi rates a dynamic range of >115 dB(A) and THD+N of < 0.008%.


With so much power on hand, and IEMs increasingly coming in 3.5 mm and 4.4 mm source connections, you'd be inclined to think that the iFi micro iDSD Signature is a good way to blow out the IEM drivers with too much power, or even simply have barely any usable volume control in the first place. Yet I found myself using the device more with IEMs on the go than with headphones, and this is where the excellent iFi iEMatch comes in. To begin with, use the 3.5 mm connection on your IEM cable and plug into the provided 3.5 mm to 6.35 mm (1/4") adapter on the single-ended output. Then be sure to have the power mode set to Eco, intended with IEMs in mind, and be sure the volume is set low, before using the iEMatch button based on whether you are using high or ultra-high sensitivity IEMs. Note that this is best done on a per-IEM basis whereby you'd use your own previous experiences with the set to determine whether it gets loud easily or not from, say, a basic dongle adapter. What iEMatch does is effectively give you a much larger range of volume control, to where you can use the micro iDSD Signature quite easily even with the likes of the notorious Campfire Audio or KZ IEMs. It's one of the very, very few times that I didn't have a background hiss with Campfire Audio IEMs such as the Saber pictured above, and I truly think iEMatch alone makes this a fantastic product for IEM users.


At this point I had listened to a wide plethora of IEMs and headphones off the iFi micro iDSD Signature and wanted to compare how the DAC performed, given the amplifier section and its various modes are clearly impressive. We saw another implementation of Burr-Brown in the iFi GO blu before, and that was a single DAC version that is also presumably a more power-efficient chipset too. This dual-DAC version makes for a warmer sound signature relative to the sterile and clean ESS Sabre sound, and it can pair well with brighter headphones and IEMs. In particular, I thought the micro iDSD Signature was very handy with the HIFIMAN Arya and the Meze Liric, even taming the HIFIMAN HE1000se briefly. This also lends more favorably to overly bassy sets, although it can risk cutting out transparency with vocals. Otherwise, I can't really tell you whether the iFi micro iDSD Signature "opens up the soundstage" as some claim!


This not being a Bluetooth device also lends more favorably to the absence of mobile apps for EQ profiles, but also I was pleased to see XBass and XSpace from the GO blu show up here in what iFi calls XBass+ and 3D+ available via toggle switches on the front. XBass+ is a purely analog signal circuit effect which extends the bass response further as seen above, with the dashed line at 0 dB being the base case with none of these effects active. We see it ending up as a bass shelf beginning at ~900 Hz down and going up nearly 9 dB at 20 Hz, although practically you will only start to notice the changes from ~200 Hz and lower. XBass+ is marketed by iFi audio as enhancing the low frequencies without muddying up the mid-range, so I grant it meets that goal well enough. It won't be to everyone's tastes, but will be a great midway point in going from a mainstream V-shaped tuning to a more neutral and accurate set, adding some fun you may find missing in the latter.

3D+ is another analog effect that is intended to open up the soundstage to make for a more holographic sound field, akin to listening to speakers instead. The goal here is to address the general "inside your head" imaging and sensation achieved from IEMs and headphones, and iFi also clarifies these technologies do not impact the clarity and resolution of the original music recordings in any way. Based on the description of the effect, I was not surprised to see an emphasized treble response rising from the lower mids but once again only becoming appreciable in the upper mids itself to add more presence to instruments and female vocals alike. The gain here is ~4 dB max, but notice how this is accompanied by recessed lows that dip further to accentuate this rise further. This makes 3D+ far more subjective in preference, and even more of a niche compared to XBass+, as well as specific headphone and IEM sound signatures.

Then there's the combination of both, doing exactly what you'd think, XBass+ and 3D+ combining to make for a stronger V-shaped tuning. The increases are closer to 4 dB on the bass side and 2 dB on the highs relative to the dip in the mids, but this can certainly take a neutral tuning and make it a completely different one. It's even more a niche option in my opinion, but I can appreciate the use case. I also appreciate there effectively being three profiles, which do at least cover what a lot of people would generally do with 5/10-band EQ. I would personally still prefer parametric EQ, if only to fine-tune some of these effects based on the headphones and IEMs I listen to, but that's where something like Poweramp (on Android) and Equalizer APO (on Windows) comes in handy. I will also mention there are two filters preset on the device, and I only noticed a tiny dip in the higher treble frequencies here, although your mileage may vary.