Setup and Performance

There is another chipset on the PCB, which I chose to focus on more here since it directly pertains to the setup and user experience. This is a Qualcomm QCC5100 series Bluetooth chipset, which iFi audio does not specifically name but we know has support for Bluetooth 5.1 connectivity in addition to all major Qualcomm-compatible Bluetooth codecs—SBC, AAC, aptX, aptX HD, aptX Adaptive, and aptX Low Latency. If I were to gander a guess, this is a QCC5121, which is a low-power, premium-tier SoC. What makes things interesting is LDAC support in addition to the unicorn that is HWA's LHDC codec. This is the first time I have seen a product with LHDC supported out of the box, although the Grell TWS-1 is another on the way. Pairing the GO blue with my phone, laptop, or PC was simple enough—just press the power button on the left side and watch the indicator LED by the headphone outputs. It will flash blue when waiting for a connection and red/blue when pairing, and turns off when paired.

The problem is the Bluetooth range, which doesn't jive well with all the engineering done with the antenna placed by the side, where you also have the plastic enclosure and no metal. Bluetooth range is quite short in the more optimal playback settings—I lost connectivity even with my phone charging in another room. It does get better with codec and playback set with stronger transmission in mind, but this is an issue customers and iFi audio have already acknowledged, and I am told a fix has already been applied to recent batches of the GO blu. It's fine if you have the source and GO blu on your person when on the move, so it is plenty functional in that regard. The iFi GO blu can also be used wired, though I suspect most won't. The provided USB cable works all the better with laptops and PCs, and it is detected automatically and even set up as the default output in Windows 10. No drivers needed here, and you get a maximum playback rate of up to 24-bits and 96 kHz despite the DAC itself being a 32-bit unit. No complaints from me, though; this is more than sufficient for the scope of this product. The other main complaint I do have is the lack of any clip to secure this to your person. This is otherwise intended to be in a pocket, by itself or with the provided fabric pouch, but how do you then use the microphone for communication? Just leaving it on, say, the desk is not that different from a more standalone product that will do better while not taking up much more room.


When in wired mode, plugged in, the iFi GO blu can be charged and used simultaneously. In this scenario, the internal battery will charge to ~80% and be held there for battery longevity, which I appreciate. If nothing is playing, the battery gets charged to 100%. The battery status indicator LED is of use here, lighting up green when the battery charge is over 60%, yellow between 10% and 60%, and red under 10%, with the respective colors flashing in a breathing mode when charging. The other indicator LED is multi-purpose, with the first set for Bluetooth pairing status as discussed above and a whole other set indicating sound effects in use. There is no mobile app support, which, while we are discussing features and expectations the iFi GO blu may fall short of, may be a potential dealbreaker, too. The company does not shy away from pointing out its strength is not with digital filters and parametric EQ, but, rather, a few analog sound effects we will discuss in more detail below.


The multi-functionality aboard extends to the switch integrated with the volume knob, and iFi audio does show what can be achieved with clever engineering in an otherwise tiny form factor. The functions themselves are self-explanatory and worked flawlessly. The switch is also contoured such that you won't easily hit it when rotating the volume knob, which is another design win. Just be aware that some of the design challenges do make it harder to make the most of the features, including the microphone you need to have somewhat close-by at least. This has led to a few aftermarket solutions, including this necklace cord accessory from MITER in black, blue, or green.


I wanted to set a baseline for the default sound signature of the iFi GO blu, especially given most of my experiences to date with these portable units have involved ESS DACs. I used the Lime Ears Pneuma IEMs pictured in the title photo on page one and further below
since the iFi GO blu will show up again in another review coming up soon and involving the Pneuma and a fancy set of aftermarket IEM cables. The test above was done with the stock IEM cable, which terminates in a 3.5 mm jack, so it was plugged into the single-ended output on the GO blu, which was in turn connected to my laptop via Bluetooth in aptX mode. I then conducted a separate test with the GO blu wired in, and that tested and measured identically enough to where this to me remains the most impressive facet with these ultra-portable units today—the sound signature over Bluetooth is right up there with wired performance. If I carefully A/B tested with different codecs and file formats, I could tell the difference, but, gosh, I would much rather just listen to music and take advantage of the enhanced portability the iFi GO blue provides.

In fact, it does better than my reference soundcard, but that in itself is not surprising. Most soundcards are less than ideal for a perfect listening experience, which is something frequency response measurements by themselves don't capture. This is why I make a point of mentioning that measurements with a soundcard don't mean I listen with it all the time too, and this is where the iFi GO blu shines by adding more detail and contrast as we progress through the lows, mids, and highs. The output impedance of under an ohm is plenty for pretty much everything, although some highly sensitive IEMs may end up with a background hiss. This was less of a case with the 3.5 mm output than the balanced output, and I recommend trying 3.5 mm first, also for longer battery life.

Speaking of which, I was quite amazed that a company's battery life metrics were for once not only met, but exceeded under normal listening conditions. The iFi GO blue is rated for ~8 hours of listening, but even the FAQs and marketing materials suggest it may be closer to 10 hours. Indeed, I regularly got 9+ hours with my typical listening volume for IEMs and headphones in LDAC mode, which was closer to 10 hours with aptX Adaptive and aptX itself. Charging the internal battery also takes under an hour if conditions are ideal since the iFi GO blu supports 1 A charging at up to 6.3 V. This means you can take your favorite wired IEMs or headphones along on even a long transoceanic flight, use the iFi GO blu for most of the flight, charge quickly on a layover perhaps, and be ready for round two! The iFi GO blu can be paired with up to eight devices simultaneously over Bluetooth, and even be connected both wired and wirelessly at the same time, though playback of course only happens from a single device.


There may not be an app, or any digital filters, but that has not stopped iFi audio from putting out some EQ signal processing. It may not be parametric or even customizable, but iFi audio made a few key features marketable by simply calling them unique names. These have thus become somewhat synonymous with the brand, so much so that anyone remotely familiar with iFi products will be looking to see if these are on the feature list, typically as a dedicated button on amplifiers. XBass is probably the most famous of these analog sound effects, and it does feel weird calling it that; it adds a generous bass boost to the sound signature. Keep in mind that different headphones, or earphones, will respond differently to the boost, so it's not like iFi audio is simply slapping on a maximum of ~8–9 dB in the sub-bass region. No, if you look at objective testing of XBass from others, you will notice that the only thing in common is a relatively smooth rise in SPL from ~200 Hz, which is where I prefer to see the bass response separated from the mids. The dotted line is steady at 0 dB, and the plot above actually has the frequency response of the Lime Ears Pneuma driven from the GO blu with XBass on relative to without, which is the dotted line itself, of course. So at least in this case, it's not just a bass boost, but a <1 dB uniform SPL drop in the mids and highs as well. Take that peak near 20 kHz with a grain of salt since it is a measurement artifact. As such, by comparison, we actually have closer to a 9 dB maximum boost here. XBass is marketed by iFi audio as enhancing the low frequencies without muddying up the mid-range, so I will grant it meeting that goal well enough. It won't be to everyone's tastes, but will be a great midway point, going from a mainstream V-shaped tuning to a more neutral and accurate set, and it adds some fun you may find missing in the latter.


My grand plan of coloring the lines based on the LED indicator color only worked here, but I went with a darker blue even so for better contrast from the white relative to the more cyan LED for what iFi calls XSpace. As the name suggests, XSpace aims to add more space to your music, effectively trying to increase the soundstage akin to a few DSP techniques. XSpace is also targeting the experience of being in a concert hall, where you are perhaps listening to an orchestra in a setting designed for acoustics and space. I am not surprised to see an emphasized treble response thus, peaking from the upper mids to add more presence to instruments and female vocals alike. It's not much, at most ~2 dB, again ignoring ends points, but notice how this is accompanied by recessed lows that dip further to accentuate this rise further. This makes XSpace far more subjective in preference, and even more of a niche compared to XBass, as well as specific IEM tunings. For example, with the Lime Ears Pneuma, I did not want to have XSpace on until I flipped on the bass boost switch on the IEMs themselves.


Or maybe I could have just done this instead! XBass + XSpace is the third and final EQ environment, and it does exactly what you'd think, making for a V-shaped tuning on top of the existing one. The increases are closer to 6 dB on the bass side and 4 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. Tread carefully, however, since tuning changes this big can affect a lot of things to where you may not like it at all. It's 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) comes in handy. It's also where I still don't see the iFi GO blu necessarily being an upgrade to anyone with the Qudelix-5K, but I can see a world where both easily coexist, with the iFi GO blu being more user-friendly from a plug-and-play perspective.


There is a secret bonus feature aboard the iFi GO blu that isn't mentioned anywhere and took some digging to find: audible beeps to indicate the mode being used, as well as a voice prompt confirming the codec in play. It can be handy for visually impaired users, and simply adds to the user experience as a whole.


I know I did not mention power output yet, but I first want to show you what's coming up in the Lime Ears Pneuma review, which includes a in mostly good ways ridiculous cable from Hapa Audio. The Knot IEM cable I have here terminates in a 4.4 mm connector on one end and 0.78 mm 2-pin connectors on the other, making it a good replacement cable for testing the Lime Ears Pneuma and iFi GO blu on the 4.4 mm headphone output. This is a balanced output using the twin mono amplifier power stages, although there is a single DAC chip rather than two as with FiiO and Qudelix. Regardless, the tangible benefits of a balanced connector are seen here, with removed ground and loop signal issues, if any, as well as an inherently higher voltage and, thus, more power output. In fact, the 3.5 mm single-ended output of the iFi GO blu already provides more power than the other analogous portable DAC/amps I have seen, up by 50–100% at that. This means I had no problem powering even demanding IEMs, practically without resorting to the 4.4 mm balanced output at all. Headphones too can mostly be handled by the 165 mW it provides when facing 32 Ω, so anything in the realm of portability will generally be fine. With the Hapa Knot cable and Lime Ears Pneuma, I was closer to 10% volume as opposed to the ~40–50% with the single-ended cable, with the iFi GO blu connected to my phone, especially seeing as how it can provide a whopping 245 mW at 32 Ω. This is why I suggested trying the 3.5 mm output first, and it will also help reduce hissing/clipping issues with sensitive IEMs in addition to preserving battery life.