First five minutes with the KZ ZS7 …
Much better balanced, tonally, than any other KZ IEM I’ve heard. Treble is far better controlled, more restrained, and quite a bit smoother than the other KZ models I’ve piddled around with.
On the downside, getting a seal on these results in an enormous amount of crackling and popping, presumably from the dynamic driver being compressed. As does ANY movement of them in/out of the ear once they’re in place. It’s obnoxious, unsettling and absolutely un-ignorable.
This could be a fault with this pair … especially as it is far more prominent on the left than the right unit. After 10-30 seconds of play the left side will “pop”, stop crackling and then sound normal … prior to which it is quieter and highly subdued on one side.
I’ll order another pair to test. But if this is how they are normally, they’re a non-starter for me as even moving my jaw can cause this popping/crackling - even without the IEMs being connected to anything.
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Edit: I’m pretty sure the left driver is just flat out faulty. The right hand unit does not exhibit this crackling/popping no matter what I do with the pressure/seal. Not that it seems to be affecting the overall sound, which is quite good, but I can’t listen to these with this crackling/popping occurring just from normal wear (never heard anything like it before).