The IO Audio Sogno was kindly provided free of charge in exchange for an honest review. I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links. The price of the IO Audio Sogno is $399 and you can buy it from Shenzhen Audio.
IO Audio
IO Audio is a relatively new brand, an earphones manufacturer that made a resounding debut with the Volare. A flagship, yet affordable, earphone with a hybrid driver configuration that was lauded both from critics and hobbyists. A well made and comfortable earphone with excellent sonic performance that punches well above its price point.
IO Audio Sogno
IO Audio is now back with their second instalment, the Sogno, another hybrid in-ear monitor that is $200 less expensive than the Volare.
Technical highlights
The IO Audio Sogno has eight drivers per side (the Volare has nine) and more specifically, 2 dynamic and 6 balanced armature drivers that are combined together with the aid of a five-way electronic and four-way physical crossovers.
The Sogno incorporates a self-developed coaxial, dual dynamic driver which consists of one 10mm and one 6mm units. The 10mm silica gel suspension mixed paper basin dome handles bass and a portion of the vocals while the 6mm treble driver is designed to optimize the impedance characteristics of the high frequencies.
Additionally, four customized balanced armature drivers ensure consistent timbre in the high frequencies, and another two customized balanced armature drivers are used to enhance the upper high-frequencies. Moreover, the sensitivity has been adjusted to reduce the need for additional frequency crossover components, optimizing the system engineering.
You can read more about the IO Audio Sogno here.
Design and build quality
The IO Audio Sogno adopts the same design and outer appearance as the Volare but with a slightly different faceplate pattern. The faceplate pattern of the Volare resembles a bush with thorns while the Sogno looks like tree branches without leaves.
The all black ear-shells are adorned with silver-metallic spots that are integrated inside the compound and look like floating. The left and right shells are marked with the letters “I” and “O” respectively while the rear part of each shell has the logo “SOGNO” printed with golden letters.
In my review of the Volare I wrote that it is one the most beautiful and unique looking IEMs ever made but I think that the Sogno looks even better and could easily win a design award.
The ear-shells are made from medical-grade resin compound in partnership with the renowned Heygears. The 3D printing quality is flawless, the Sogno is exceptionally well made and smoothly finished without any visible faults in the molding.
Wearing experience
The ear-shells have an ergonomic, custom-like shape with a mildly extending sound tube. They are lightweight and compact enough, despite the driver count, and fit exceptionally well.
The ear-shells just mildly protrude outside the ears but the overall feeling is that of a very comfortable earphone that isolates well and can be worn for many hours without causing any kind of discomfort.
The cable
The IO Audio Sogno is equipped with a high quality cable that is similar to that of the Volare. Their difference is that the cable of the Sogno comprises four strands of cross-braided 6N OFC oxygen-free copper silver-plated wire instead of eight.
It is a modular cable with the 2-pin interface, the package includes 4.4mm, 3.5mm and 2.5mm plugs. The cable has the exact same issue as the Volare’s cable where it can get stuck in the stem of the modular plug.
This is a well made cable that is more lightweight than that of the Volare. It is quite flexible, it doesn’t get easily tangled and has low microphonic noise, however, the splitter is a little bit heavy and pulls the cable downwards.
Accessories
The Sogno comes packed in a somewhat simpler box than that of the Volare but it is as generously accessorized despite their price difference.
The package includes a high quality and luxurious carrying case that looks like a jewelry box, a separate cable storage bag, a cleaning cloth and five different types of ear-tips in three sizes each. Each set of ear-tips is stored in its own small plastic box, a total of five boxes. Don’t forget to remove the two foam inserts inside the carrying case to make space for the earphones and your favorite USB DAC dongle.
Important note regarding the ear-tips
The package includes five sets of IO branded ear-tips that are labeled as TW45, TW40, TW43, ST50 and F49. All of them are silicone ear-tips except for the F49 that are memory foam. The rest are a mix of medium and wide bore ear-tips, the most narrow is the ST50 and the wider is the TW40.
I tested all sets of ear-tips and found them equally comfortable but they gave very mixed results regarding the frequency response of the Sogno and especially the bass.
The only set of ear-tips that worked well and had solid bass extension (in accordance with the published measurements) was the TW40. All others sounded bass-light and thin to the point that the Sogno completely lacked sub-bass and bass.
I also experimented with the Penon Liqueur and the Divinus Velvet wide bore ear-tips. The Liquor gave better sub-bass extension and a more balanced frequency response than all stock tips while the Velvet’s were the best of all by a fair margin. Solid sub-bass, neutrally toned and full bodied lows, balanced mids and not that bright treble.
It seems that the IO Audio Sogno is very tip sensitive and someone must experiment with all stock and many aftermarket ear-tips in order to find the correct tonal balance. Please note that the IO Audio Sogno has excellent sub-bass extension and full bodied bass. If you can’t hear it, then there is something wrong with the tips you are using.
My listening impressions apply to the IO Audio TW40 and the Divinus Velvet wide bore ear-tips.
Power requirements
The IO Audio Sogno has 12.8Ω impedance with 126.5dB/Vrms of sensitivity so it is ridiculously easy to drive. However there is a catch, the source must be dead silent with an output impedance as low as 1.5Ω (or ideally lower) and a wide margin of volume adjustment so it doesn’t get loud too fast. For this review I have used the iBasso DX180, FiiO M23 and Cayin N6iii DAPs.
Listening impressions
Direct comparison notes with the IO Audio Volare are included in the following text.
The IO Audio Sogno can be seen as a more Hi-Fi tuned version of the Volare that has a strict adherence to the Harman target curve. For the Sogno, IO Audio opted for a more balanced and tonally accurate tuning with a slightly less emphasized bass, a touch more prominent treble and the same kind of midrange recession as in the Volare. In this regard, the Sogno can be still considered as a mildly “V” shaped earphone but to a lesser extent than the Volare and without lacking that much mid-range presence.
The sub-bass is strong and powerful but not that boosted to sound dominant over the other frequencies. The bass has a more natural and precise tuning than the Volare. The low-end is still not, strictly speaking, neutral-reference but it has better tonal accuracy than the Volare.
The bass is carefully balanced to accommodate both critical and casual applications. The Sogno has good fidelity when it comes to reproducing the low-pitched instruments of the symphony orchestra and at the same time it can sound very exciting and enjoyable with modern vibes.
The dynamic driver of the Sogno is more technically capable than that of the Volare so do expect a bass that is tight and controlled with the right timing and very good layering. The bass of the Sogno is more clean and well defined than someone would expect for the category, while it is surprisingly weighty and elastic. The driver can move a lot of air, the bass is punchy and impactful while it has a fast recovery so it can easily adapt to a wide range of sudden dynamic and speed variations.
More listening impressions
The mids are more prominent towards the upper mid-range, making for a sparkling and energetic approach where certain overtones get more emphasized than the others. This can lead to potential listener fatigue with some recordings or sources but only if your hearing is too sensitive in this region. Most times, and especially with classical music, the mid-range sounded tonally accurate with a natural and organic timbre minus some traces of artificiality in the higher harmonics.
The presentation is realistic and lifelike enough with lush yet well defined textures. The music has plenty of natural flow and nothing really stands between it and your ears. The Sogno is melodic and expressive with plenty of excitement for listening to electronic tunes and good emotional depth for classical music. The overall sonic performance is not much different than that of the pricier Volare.
The treble and upper high frequencies are where the Sogno sounds much different than the Volare when it comes both to their quantity and quality. The Sogno is more energetic and luminous than the Volare but not that so as to sound harsh or piercing. It is certainly brighter and more sparkling than the Volare but it still retains a level of control and smoothness.
And more
The Sogno is faster and marginally cleaner than the Volare, but while it gives the first impression of better detail retrieval, it doesn’t take long to realize that the Volare is more capable in this regard. The electrostatic drivers of the Volare are superior to the BA drivers of the Sogno as they sound smoother and less grainy with better resolution and refinement.
Still, the Sogno sheds more light in the music and sounds fresher and more exciting than its brother. The timbre is mostly natural but you can notice a few traces of metallic sheen here and there. The texture weight is in consistency with the lower frequencies.
The soundstage is where the Sogno pulls ahead both from the Volare and much of the competition. It is so wide and spacious that it reminds of a full sized, open-back headphone. The stage is extended, but not artificially stretched, with precise imaging and separation as well as surprisingly satisfying depth layering. Grand and immersive enough, it can handle all kinds of large scale music and at the same time is ideal for movie watching and gaming.
In the end
The IO Audio Sogno might be less expensive than the much acclaimed Volare but it is not less impressive. The Sogno has a neutral-balanced tuning aided by excellent technical performance, making it ideal for both critical and casual listening without severe takeaways. This is a true all-rounder earphone that pairs well with most sources and sounds fine with all kinds of music.
The Sogno is exceptionally well made and very comfortable, it has a striking appearance and comes with one of the best accessory packs in the market. IO Audio made a strong debut with the Volare but their second installment is no less spectacular. The Sogno stands out as a very competitive and worthy option in a heavily populated market and gets easily recommended.
Copyright – Petros Laskis 2025
+ Neutral - balanced and cohesive
+ Bass extension and technicalities
+ Expressive mids and energetic treble
+ Natural timbre without much artificiality
+ Clarity and transparency
+ Wide and immersive soundstage
+ Full bodied textures
+ Comfortable and lightweight
+ Good passive noise attenuation
+ Striking and unique appearance
+ High quality modular cable
+ Very well made
+ Generously accessorized
+ Competitively priced
- Some traces of metallic sheen
- Not the most refined textures
- The sound is extremely ear-tip dependant
- Potentially fatiguing upper mid-range
- The splitter of the cable is a little heavy
- Requires high quality sources to shine
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