SOUL is one of the earlier adopters of true wireless earbuds, launching a few of such models way back in 2017. That was when the first-generation ST-XS was made available. Over a year later, ST-XS2 was launched, and retails in Singapore at S$169.90. I have received a review unit to give my opinions. Since its launch mid-2019, the true wireless market has grown in leaps and bounds, so let’s see if this model is still relevant in 2020.
Unboxing and Operations
The retail unit unfolds to reveal additional product information and the earbuds behind the clear cover. There are different sizes of ear hooks and eartips in matching colours. Other accessories include a carabiner and short USB-C charging cable. I feel comfortable wearing them, the size is right and I don’t feel too tight on the ears, the ear hooks feel unobtrusive such that I don’t know if they are actually gripping my ears. The eartips also isolate external noise really well without requiring me to adjust – I just pop the earbuds in and the seal is done. I really cannot hear much environment noise around me, I need to pay extra attention to check blind spots before moving around, and definitely need to remove them before I can carry out a conversation (or turn on transparency audio mode).
The charging case is made of plastic with a piece of matt aluminium deco piece in the middle. The case snaps shut by clip instead of magnets, so it is unlikely that the case will open in normal situations. Even if it does, the earbuds are held in place by magnets so they won’t drop out.
There is a single physical button on each earbud. The button is quite stiff, so I find it very uncomfortable to click it as it pushes the eartip further into my ear canals. Click once to play-pause, click twice to go to next track (there is no option to go to previous track), click 3 times to initiate smart assistant on the phone. The ST-XS2 has a Transparency audio mode which you can activate by press-hold the button for about 1 second. More on the Transparency audio mode quality.
On the case, there is a single LED. To interpret the remaining battery amount, watch the number of blinks: each blink denotes 25%, so 4 blinks means 100% battery. The charging case holds up to 20 hours of battery, while the earbuds can do 5 hours, totalling 25 hours in all.
Pairing the ST-XS2
The ST-XS2 activates pairing automatically whenever there is no device paired. The left earbud is the primary earbud that will be paired to the Bluetooth device, while the right earbud will connect to the left earbud for stereo sync. What this means is that if the right earbud gets disconnected or goes into the charging dock, the left earbud can continue to operate, but not the other way round. To reset the ST-XS2, follow this instructions on the video here.
Transparency Audio Mode
The SOUL ST-XS2 has one of the more unusual transparency mode I have tested. Activating it will reduce the playback volume slightly, but no impact on the sound balancing. What I get from the transparency audio mode is extreme heightened sense of hearing at the upper frequency, but suppressed at the mid and lower frequency. It feels like experiencing ASMR: typing on a keyboard goes clacking in my ears, snapping or clapping softly sounds like raindrops, footsteps and conversations are amplified. Sitting in front of a fan, you get the wind-in-mic effect. There is poor spatial imaging so it’s difficult to pinpoint the true direction of the sound you hear. Everything sounds like it’s close to you rather than from a distance.
The transparency audio mode can sound really noisy in a busy place like food centre where the wok frying sounds supercede all other noise. But I can live with enabling it when using at home, as it allows me to take notice of any noise around the house. Wearing it while walking in the neighbourhood, I can hear little high pitch details around me, and making me feel like some superability human.
As mentioned earlier, the primary earbud is the left one, so only the left earbud mic is used for call conversations. When testing the ST-XS2 for calls, they sound muffled, lack clarity. Again, once I cup my hand around my cheek, the clarity goes up exponentially. In windy situations (e.g. sitting in front of the fan), the mic totally cannot pick up my voice.
Fitted with 6mm dynamic driver and supports AAC and SBC codecs, the ST-XS2 delivers good clarity, which heightens the instrumental details occupying the upper frequency, like percussions and vocal breaths. These earbuds are capable to delivering details thanks also to the good seal. Bass is also well-balanced with pumps that give presence but do not cloud the sound. Sub-bass is not exaggerated unlike Jabra Elite 75t, but you still get the booms if the mixes have strong sub-bass. I would say the ST-XS2 is a pretty well-balanced earbuds, delivering good treble clarity but not too pushy. Same for bass, good feel without drowning the highs. Midrange is not too forward but neither is it absent unlike RHA or Sennheiser.
The instrumental separation is also good, so I can easily hear them in spatial positioning. Sound staging is more wide and close, towards the ears instead of in front of me. The ST-XS2 is good for instrumental genres like Classical, Movie Soundtracks, Jazz. The good seal means you can enjoy details without pushing the volume too high.
Compared to other True Wireless
At a price range of S$169.90, the ST-XS2 is a reasonably-priced earbuds, sitting below the popular brands like Klipsch, Plantronics and Jabra, competing with mid-tier brands like Sudio, Pamu, Audio-Technica ATH-CK3TW. Here are some general differences when compared to similar-priced models (S$100-200):
Sudio Fem – the ST-XS2 delivers more bass, with less sparkling treble. If you like more treble, get Fem. For more bass, pick ST-XS2.
Creative Outlier Gold – price-value and battery life, the Creative is at an advantage. Sound-wise, to each his own, but the Outlier Gold is more energetic sounding and fatiguing, while ST-XS2 is more comfortable.
Audio-Technica ATH-CK3TW – The CK3TW has way more deep bass level with a little more sizzle in the treble. Between the two, I slightly prefer the Audio-Technica sound that is more fun to listen to, but the ST-XS2 has better water resistance for active use. In any case, an EQ tweak will put them on par.
Pamu Slide – The Pamu has more bass, less sparkling treble, hence slightly darker. The casing is huge, which is a put-off to many, but the Pamu Slide Mini makes it right.
Among the sports earbuds reviewed in recent months, the ST-XS2 is one of the more enjoyable in audio, and comfortable in fit. It gives me great security in wearing it during runs, and achieves good musical balance without fatigue. The bass is not as overwhelming as some other brands, but I do prefer balance. The plastic case and the manual snap mechanism casts some doubt in the durability, and the call quality may not be adequate, so I would get them only if I’m happy with the specific positive features mentioned.