Although very similar in sound signature to ZS5, the ZST have their own pros and cons. These are some of the best earphones in terms of clarity and detail, but their pierce can be unbearable for many users, myself included. The bass is tight, but not deep enough for my taste. All of this creates an initially impressive experience, concluded with some fatigue and an urge to replace them with something more mild and natural.
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I always find the memory wires to be extremely annoying. It takes too much time and effort to position the earphones properly into the ear and even when they're inside, they don't sit flat against the ear and stick out a bit and are very easily pulled out.
Lows / Bass
The bass is very balanced and controlled, but it's also underwhelming and overrun by the super-bright highs. It's more than enough for contemporary vocal-oriented music, but for electronic music this is just not enough. Depth-wise, they are similar to ZS5 but slightly shallower.
Mids / Vocals
The mids are highly impressive, and actually very similar to ZS5, to the point where it's really hard to tell them apart. The details is quite extraordinary, but I feel like the ZS5 manages to pinpoint microdetail quite better than ZST. Along with the great vocal clarity, comes some unsatisfying pierce that afflicts vocals, especially female vocals, and high-pitched instruments.
Highs / Treble
They highs are very sharp and crisp. They are also extremely piercing. Depending on how sensitive your hearing is, you might feel discomfort and fatigue after using these earphones for a while, especially if you're listening on medium/high volumes. Superb calrity and tonally accurate, except that the treble is very bright, far brighter than what I would consider enjoyable.