Synergy
Efficiency
The Hidizs ST2 Pro Nebula features a sensitivity of 108 dB/Vrms and an impedance of 32Ω, though with an integrated DAC and amplifier its relevance only comes into play if you plan on cable rolling the drivers.
With its total output of 70mW + 70mW at 32Ω, the ST2 Pro Nebula ensures consistent power delivery and performance across different setups, whether connected to a phone or laptop.
Its efficiency is impressive, providing excellent loudness and power management without requiring high-output sources.
Even at lower volumes, the bass remains dominant, maintaining its thumpy and engaging presence. Vocals, however, are more recessed at these levels, taking a backseat in the overall mix.
At higher volumes, vocals gain more presence and occupy a better stage, though the bass still takes center stage. The treble remains stable and unaffected by volume changes, maintaining its energetic yet controlled tone regardless of the playback level.
Pairings
Using an aftermarket cable with the Hidizs ST2 Pro Nebula noticeably changes its sound signature, leaning further into a V-shaped profile.
The midrange becomes more recessed, with bass and treble overpowering it even more, making me stick with the stock cable at all times.
With the stock cable, I tested the ST2 Pro Nebula on an iPhone 16 Pro, Android phones, and a laptop. Compatibility was seamless, requiring no additional apps or drivers, essentially just plug and play with minimal impact on battery life.
The IEM proved to be highly efficient, with none of the devices needing volume levels higher than 40% to reach a comfortable listening level. The ES981AC Pro chip in the cable ensured consistent sound quality across all devices, leaving no noticeable changes in the overall performance.
Additionally, there was zero static, distortion, or interference during use, providing a clear and uninterrupted listening experience. The ST2 Pro Nebula delivered its full sound signature effortlessly, regardless of the source device used.
Select Comparisons
MOONDROP May
Technical
The MOONDROP May utilizes a hybrid driver setup, combining one dynamic driver and one planar driver. This configuration aims to provide a balanced performance across bass and treble frequencies.
Its dynamic driver features a sapphire-evaporation diaphragm, a material that enhances durability and precision. This advanced technology contributes to the May’s capability to handle full-frequency audio with minimal distortion.
Complementing this is the 6mm annular planar driver, dedicated to treble and upper frequencies. This unique addition brings a detailed and nuanced high-frequency response to the overall sound signature.
Design
The MOONDROP May features a faceplate with a club-like pattern that provides a unique texture and look. Its shiny finish adds a touch of refinement without being overly flashy.
The black translucent shell allows the internal drivers to be faintly visible under certain lighting conditions. This design choice gives a subtle hint at its hybrid driver setup.
The faceplate incorporates variations in the club pattern, with some filled-in stripes and others hollow, alongside the “May” branding. These small details give the MOONDROP May a distinctive but understated aesthetic.
Performance
The Hidizs ST2 Pro Nebula offers a bass experience aimed squarely at bass enthusiasts, delivering punchy and impactful sub-bass and mid-bass. In comparison, the MOONDROP May’s bass feels less dynamic but brings better control.
The ST2 Pro Nebula has a more natural midrange timbre that lends a sense of authenticity to its vocals. The May suffers from an artificial sharpness in its mids which feels unnatural despite the clarity boost.
Treble performance leans in favor of the May, which boasts better extension and retrieval of microdetails, making fine nuances in tracks more audible. The ST2 Pro Nebula’s treble is bright and energetic but can verge on fatiguing along with its lack of air, leaving the upper frequencies feeling less open and refined.
The soundstage of the May outperforms the ST2 Pro Nebula, offering better width and imaging accuracy, creating a more spacious presentation.
The ST2 Pro Nebula has a more intimate, in-head stage, though it compensates with strong separation that keeps elements from becoming congested in busy tracks.
It also has more consistent dynamics across volume levels, keeping the bass and treble stable. The May struggles with tonal balance, often shifting the emphasis depending on how loud the music is played.
Overall, the ST2 Pro Nebula feels more cohesive, with a sound signature that blends well across its frequency ranges. The May, while technically impressive in some aspects like treble and soundstage, can feel less unified due to occasional disjointedness between its bass, mids, and treble.
SIVGA Que
Technical
The SIVGA Que utilizes a single 10mm beryllium-plated diaphragm dynamic driver. The driver is known for its rigidity and lightweight properties, allowing the driver to deliver quick and responsive sound.
The Que uses a single-magnet, dual-cavity driver structure, a simpler design compared to its more multi-driver sibling IEMs. This configuration focuses on optimizing sound cohesion and bass performance.
SIVGA highlights their tuning of the Que, emphasizing a warm and bassy sound signature. Their approach prioritizes creating an enjoyable and laid-back listening experience over analytical precision.
Design
The SIVGA Que combines a unique aesthetic with SIVGA’s signature design elements, instantly recognizable to those familiar with the brand. Its faceplate is crafted from white American maple wood, featuring the SIVGA name carved into it for a refined touch.
The faceplate is smooth and silky to the touch, showcasing the craftsmanship and attention to detail in its construction. However, as with other wooden faceplate designs, there may be concerns about durability over time.
The shell is made from zinc-alloy metal, split into two parts: the faceplate side and the main chamber. It features two vents to alleviate ear pressure and high visibility left-right labels to avoid any confusion during cable connections.
Performance
The SIVGA Que delivers a powerful bass performance, with rumbles and punch that feel satisfying and detailed. However, the ST2 Pro Nebula takes bass a step further with more impact, energy, and thumpiness, making it more engaging and enjoyable for bass enthusiasts.
The Que provides warm and thick vocals with a natural timbre, offering a laid-back and relaxing listening experience. The ST2 Pro Nebula presents a cleaner but recessed midrange, allowing its bass to dominate the overall sound signature.
The treble of the SIVGA Que is smooth and sibilance-free, providing a safe and inoffensive presentation. Whereas the ST2 Pro Nebula’s treble is brighter and more energetic, offering better detail retrieval but at the cost of potential fatigue during longer sessions.
Both IEMs provide an intimate, in-head experience, though the Que’s stage feels more confined. The ST2 Pro Nebula slightly improves separation, ensuring instruments remain distinguishable even in busier tracks.
Imaging on the Que feels cramped, with instruments positioned too close together, lacking depth and layering. The ST2 Pro Nebula also has a limited stage but offers better placement and separation, making it feel more cohesive in its presentation.
Dynamics are more balanced on the Que, with no frequency range overpowering the others. In contrast, the ST2 Pro Nebula leans heavily on its bass, occasionally overshadowing the mids and treble, but it maintains more consistent performance across varying volumes.
My Verdict
The Hidizs ST2 Pro Nebula offers a powerful and engaging listening experience, with bass that stands out for its punch and rumble.
Its natural timbre, bright treble, and cohesive presentation make it a good choice for listeners who enjoy energetic and impactful sound signatures.
With its built-in ESS DAC, seamless compatibility, and efficient performance across devices, the ST2 Pro Nebula provides convenience and versatility for first-time upgraders.
Hidizs ST2 Pro Nebula Technical Specifications
- Driver Type: One (1x) dual-magnetic dynamic driver
- Plug: USB-C DSP with ES9281AC Pro chip (either 0.78mm or MMCX terminations)
- Frequency Response: 20Hz – 40kHz
- Impedance: 32Ω
- Sensitivity: 108 dB/Vrms
