Review: Supra Zero-TX TWS

Just over a year ago, the Supra Nero-TX made a significant impact, delivering impressive audio quality that belied its 900 SEK price point. Supra / Sound of Sweden has continued its pursuit of exceptional audio value. By focusing on component quality and streamlining non-essential features, the new Zero-TX models aim to provide the best sound for the money, at almost half the price of the already affordable Nero-TX.

But does the Zero-TX truly deliver on this promise?

Initial impressions of the Zero-TX are of simplicity and functionality. The design is straightforward: black, somewhat elongated, and reminiscent of headphones designed with a focus on core performance. Cost savings are achieved by omitting features like aluminum accents, reflective surfaces, multi-functional charging cases with power forwarding, wireless charging, and most advanced audio codecs. However, the tradition of using military-grade aircraft composite for the housing continues. While this may sound like marketing hyperbole, the material contributes to the overall durability of the earbuds. Weighing in at a mere 3.9 grams each and featuring an IP4 rating for sweat and moisture resistance (a feature recently introduced in Apple’s third-generation AirPods, which retail for over 2,000 SEK), the Zero-TX offers a compelling combination of lightness and resilience.

Pairing the earbuds with a Bluetooth source, such as a smartphone, is a quick and easy process. The Zero-TX consistently connects rapidly after the initial pairing, which is beneficial given the absence of firmware update capabilities. The fit is secure, thanks to the lightweight design and the elongated shape that allows the earbuds to sit comfortably within the ear canal without feeling bulky or prone to falling out (unlike some models, such as the Panasonic SZ-500W).

Prior to evaluation, the headphones were subjected to approximately 12 hours of burn-in using pink noise and a diverse playlist to loosen the components. As always, selecting the largest silicone tip that comfortably fits the ear is recommended to optimize bass response. The bass performance of true wireless headphones has historically varied, due in part to design constraints that limit the speaker diaphragm size to around 10 mm. The Zero-TX utilizes a diaphragm 40% smaller than that of the highly regarded Technics EAH-AZ70. To assess the impact on bass reproduction, a diverse selection of reference tracks was employed.

In short, the Zero-TX delivers impressive sound quality, particularly given its price point. The headphones can achieve substantial volume levels while maintaining clarity and power that exceeds expectations for its class. The bass response in Carolina Perez Wallin‘s cover of Kent‘s Pärlor is surprisingly deep, complemented by a near-perfect midrange with clear vocals and natural sound reproduction across the frequency spectrum. Scarlet Pleasure‘s What a life is reproduced with ease. The Zero-TX may not be the ideal choice for those seeking pronounced bass emphasis, particularly in genres like Hip Hop, where balancing deep bass and rap vocals can be challenging.

It’s challenging to find significant faults with the Zero-TX in terms of audio performance. The engineering and component selection choices deliver substantial benefits without significantly increasing the price. The trade-off lies in the simpler design and the omission of features like high-resolution audio codecs. Implementing aptX and its HD variants involves licensing fees to Qualcomm and requires their chips. While Sony’s “license-free” LDAC codec could be an option, participation in their program is required. The Zero-TX supports SBC and AAC codecs, which provide adequate performance for many users, particularly Apple users. Sound by Sweden also mentions “high resolution codec up to 16 bit 48 kHz” support. The SBC codec is continuously being developed, and newer phones often incorporate versions capable of playing LPCM Audio data up to 352 kbit/s, which is acceptable for an affordable headphone, even if not quite sufficient for Tidal’s uncompressed stream of 700 kbit/s.

Another minor drawback is the microphone quality for phone calls. Cost savings have been achieved by forgoing advanced multi-directional microphones with noise reduction found in more expensive models. Phone calls are functional, but the audio may sound slightly distant and tinny to the recipient. However, the caller will hear the other party clearly. The earbuds can be used individually for calls or monitoring purposes while cycling, allowing for awareness of traffic. Podcasts and audiobooks are reproduced accurately.

Battery life is respectable, offering approximately five hours of playtime on the earbuds, with the charging case providing four additional charges for a total of 25 hours, which should meet most users’ needs. The headphones also support fast charging via USB-C, a significant advantage. Charging the completely discharged headphones and case to full capacity takes approximately one hour.

In conclusion, Supra has delivered another compelling product. The Zero-TX offers even greater value than the already affordable Nero-TX (a comparison to the slightly more expensive and feature-rich Nero-TX Pro will be forthcoming). The Zero-TX offers a comfortable fit and a refined case design. Given the price point and the sound quality, the value proposition is undeniable. While the Nero-TX may offer a slight improvement in overall sound, the difference is not proportionate to the price difference. The Zero-TX does not surpass our reference model from Bowers & Wilkins – but is the B&W PI7 truly 8-9 times better for the money? Certainly not.

Ultimately, the ideal choice depends on individual needs, budget, and priorities. While the pursuit of absolute fidelity requires a significantly higher investment, the Zero-TX represents exceptional value. For those with a limited budget seeking the best possible sound quality in the true wireless category, the Zero-TX is a standout option. Despite minor shortcomings, the overall performance warrants a top recommendation.