The personal audio landscape is continually evolving, but few brands manage to carve out a distinct aesthetic and sonic identity quite like Sendy Audio. Since capturing the industry’s attention with their award-winning AIVA planar magnetic headphones in 2019, the manufacturer has steadily refined its craftsmanship. Today, the spotlight falls on their latest release: the Sendy Audio Apollo Pro, an upgraded, open-back planar headphone retailing at $449.00.
Positioned strategically within the brand’s lineup just beneath the Egret and the AIVA 2, the Apollo Pro shares its lineage with the original Apollo model reviewed in early 2022. Despite its "Pro" moniker—a label traditionally reserved for clinical, analytical studio gear—the headphone presents a distinctly musical, non-fatiguing approach to high-fidelity listening.
Main Facts and Specifications
The Sendy Audio Apollo Pro represents a significant engineering revision over its predecessors, combining advanced driver technology with meticulous ergonomic design.
- Driver Type: Custom 78mm planar magnetic driver with a nanoscale composite diaphragm.
- Diaphragm Thickness: Sub-800 nanometers, utilizing a sandwich structure.
- Weight: 354 grams, housed in an aviation-grade aluminum and genuine Zebrawood chassis.
- Connectivity: 4.4mm balanced stock cable featuring a triple-hybrid strand geometry (silver-plated copper, Furukawa OFC, and enameled gold-plated copper).
- Price: $449.00.
- Core Strengths: Exceptional soundstage imaging, organic and warm vocal presentation, highly comfortable lightweight construction, and robust micro-detail layering.
Chronology of Innovation: From AIVA to the Apollo Pro
To understand the significance of the Apollo Pro, one must look at the trajectory of Sendy Audio. Founded as a subsidiary of Ultrasone and high-end OEM specialist before branching out independently, the company initially flew under the radar. That changed dramatically in 2019 when the original AIVA planar magnetic headphones secured a prestigious Japanese VGP award, putting Sendy Audio on the global map of audiophile manufacturing.
While the AIVA proved that the company could build visually stunning, wood-backed headphones with capable planar drivers, subsequent releases sought to diversify their sound signatures. The original Apollo, launched in February 2022, favored a warmer, more bass-forward presentation.
The Apollo Pro, introduced as an evolution of that 2022 blueprint, pivots toward a more balanced, refined, and technically capable iteration. Rather than chasing raw bass impact, Sendy Audio utilized advanced manufacturing processes to target speed, responsiveness, and consistent frequency response matching across units.
Engineering and Supporting Data: The 78mm Nano-Scale Driver
At the heart of the Apollo Pro lies its custom 78mm planar magnetic driver. What sets this driver apart from conventional designs is Sendy Audio’s application of EB (electron beam) evaporation deposition technology.
This advanced manufacturing technique laminates aluminum circuits onto a nanoscale composite diaphragm. The resulting sandwich structure measures less than 800 nanometers thick, designed to offer precise vibration control and optimized structural segmentation.
Acoustic Characteristics & Metrics
- Impedance and Power Efficiency: While planar headphones traditionally demand substantial power reserves, the Apollo Pro’s lighter driver assembly responds fluidly to desktop setups such as the SMSL SU-X and SH-X stack, as well as portable powerhouses like the iFi audio iDSD GR2 and Questyle M18i Max.
- Frequency Response Behavior: Testing reveals a remarkably flat and neutral low-end response between 60Hz and 150Hz. Energy dips gradually below 40Hz, reaching an inaudible threshold near 22Hz. This prevents sub-bass bloat, ensuring that bass notes remain distinct and clear without bleeding into the lower midrange.
- Distortion and Consistency: Because the EB evaporation deposition technique applies conductive traces with high precision, driver matching between left and right channels is exceptionally tight, directly translating to the headphone’s standout imaging capabilities.
Design, Build Quality, and Ergonomics
One of the most striking aspects of the Apollo Pro is its physical footprint. Tipping the scales at a mere 354 grams, it challenges the industry norm where planar magnetic headphones frequently exceed the 400-gram threshold.
Materials and Aesthetics
Sendy Audio has long been celebrated for its woodworking, and the Apollo Pro is no exception. The earcups are crafted from refined, polished Zebrawood, featuring a spiral perforated metal grille that protects the driver while lending the headphone a semi-open-back aesthetic.
The entire structural framework—including the yokes, size adjusters, and dual arched metal spring strips on the headband—is constructed from aviation-grade aluminum finished in a sleek black anodization. Even minute details receive attention, such as white brand logos engraved on the tips of the fasteners.
Future-Proof Comfort
Ergonomically, the Apollo Pro shines through thoughtful design choices:
- Replaceable Headstrap and Pads: Unlike many competing headphones where degraded headbands or pads render the unit obsolete, the Apollo Pro features an easily replaceable, bump-textured leather headstrap and a four-point spin-on pad mounting system.
- Hybrid Stock Pads: The ear pads utilize a hybrid construction consisting of perforated leather on the interior for breathability, skin-friendly velvet, and a lambskin leather outer shell. The fast-responding internal foam molds rapidly to the contours of the listener’s head.
- Clamping Force: The low clamping force, combined with the low overall weight, eliminates hot spots and pressure points, making multi-hour listening sessions effortless.
Sound Impressions: A Sophisticated Sonic Profile
Evaluated primarily through a reference desktop chain comprising the SMSL SU-X DAC and SH-X amplifier, the Apollo Pro reveals a character defined by relaxation, spaciousness, and organic warmth.
1. Bass Response
As noted, bass heads seeking visceral, chest-rattling sub-bass rumble out-of-the-box may find the low-end tuning restrained. The Apollo Pro favors speed and articulation over sheer quantity. The bass is clean, flat, and non-interventionalist. However, planar enthusiasts will be pleased to discover that the driver responds exceptionally well to equalization, accepting low-end boosts gracefully without breaking a sweat.
2. Midrange Mastery
The midrange is where the Apollo Pro establishes its distinct personality. Imbued with a touch of organic warmth—particularly prominent in male vocal ranges—the presentation feels rich and chesty without crossing into artificial congestion. The tuning leans away from sterile neutrality in favor of an approachable, long-term listening profile that remains composed and urbane across complex vocal tracks.
3. Treble and High Frequencies
High frequencies are extended gently, offering sufficient energy to maintain air and detail without introducing harshness or sibilance. Listeners sensitive to treble fatigue will find the Apollo Pro’s smooth top-end tuning a welcome relief, though those hunting for ultra-revealing analytical sparkle might crave a touch more extension at the absolute top.
4. Soundstage and Imaging
The standout technical achievement of the Apollo Pro is its soundstage. Offering generous width and depth, it excels in spatial positioning and instrument separation. Thanks to the precise driver matching achieved during manufacturing, listeners can easily pinpoint individual elements within a complex mix, making the headphone a surprisingly capable tool for spatial dissection despite its relaxed overall tuning.
Official Perspectives and Market Implications
While Sendy Audio markets the Apollo Pro under a "Pro" designation, reviewers and industry observers note that its aesthetic beauty and musical, non-clinical tuning position it more as a luxury consumer headphone designed for immersive, extended listening rather than a sterile studio monitor.
The inclusion of a lavish triple-hybrid stock cable (combining silver-plated copper, Furukawa OFC, and gold-plated copper) alongside a sturdy leather carrying case underlines the brand’s commitment to delivering a complete, premium out-of-the-box experience.
Market Implications
Priced competitively at $449.00, the Sendy Audio Apollo Pro enters a fiercely contested market segment dominated by planar offerings from brands like HIFIMAN and Verum Audio. However, by combining genuine exotic wood craftsmanship, a featherlight 354g chassis, user-serviceable components (replaceable pads and headstraps), and a fatigue-free organic sound signature, Sendy Audio has carved out a compelling niche.
For audiophiles prioritizing comfort, build quality, and an organic midrange presentation over thunderous bass and hyper-analytical treble, the Apollo Pro stands out as a formidable contender in the mid-tier planar market.
