I equd my zs7 to sound like the **** In terms of frequency response, using audiobudgets graphs, to confirm if i have a defective unit. Bass is pretty good, mids are great, just like on my unit.
Then comes the sound upper treble onwards; treble is just off putting, it sounds somehow congested, imaging is smeared over. They don't lack treble. Its like there is a hole in the treble. I would describe the sound as irritating. Because you know these are some very well equipped iems. But just manage to miss the mark.
On the bright side they do have good balance, mids and are pretty cheap, sound superb with rock music.
Do u use an amp for the ****? I find the piezo drivers in it require some juice to get the details and brightness in the treble.