The umpteenth IEM to join the already teeming line-up is the KZ ZS4, which joins the ranks of the manufacturer’s offerings with a low price and a basic hybrid approach that includes one dynamic driver and one balanced armature.
The new KZ ZS4 join the “ZS” ranks, which has so far been used for flagship models such as the ZS6 or the ZS10. Curiously enough, KZ skipped the “4” number a year and a half ago, when it launched the ZS5, only to resurrect it now to launch a lower-end IEM.
It seems KZ created an evolution of the ZS3, as the ZS4 has anatomically shaped shells similar to those of the previous model. Even the “left” and “right” text is similar. The cable is removable and uses the usual 2-pin connector design.
Inside the plastic shells are a single 8 mm dynamic driver and a balanced armature (#30095, for those curious about it). According to the company, the combination of this specific dynamic driver and the housing design makes it possible to reach low frequencies with great impact – I will test this claim myself in the future as usual.
The claim that frequency response goes from 20 to 40,000 Hz is not entirely reassuring on this front, as headphones by KZ with good bass extension always claimed to reach far lower frequencies. Other technical info include impedance, rated at 18 Ω, and sensitivity, rated at 101 dB.
KZ piques my interest with the “26 dB noise reduction” claim, as this would make the ZS4 one of the best isolating headphones in its class. Once again it is something that needs first-hand (well, first-ear) testing.
All in all this seems like it could theoretically be a good contender in the sub-$30 arena, but we’ll have to wait and see how it performs.