Truth is, I'm speechless with the VC02s. Shocked. But I realize I have to get over from being stunned by their awesomeness to be able to describe them well and how well they really perform.
Note: This would be my first attempt to write a review as I really like them and want to share others how awesome they are!
Clarity, I think is the most notable trait they possess. There is zero sign of muddiness or any hint of any part of the frequency clouding the whole spectrum. While they do not belong to the "enhanced (bass usually)" group, you can easily hear every instrument that is present in the recording. Not only hear every instrument, but they also effortlessly render what every instrument is doing. I have lots of technical music (mostly progressive/extreme metal to be specific) that have lots of busy guitar parts in the background in my playlist that mediocre (in SQ) IEMs won't be able to handle pretty well and the VC02 just effortlessly renders them "all". They have just the enough soundstage to have room for every instrument to be heard and understood properly.
The highs are crisp and extended well, although not as I would define crystal clear like HE-400s' top-end extension, but HE-400s have a mid-high dip which makes them sound restrained or its timbre unnatrual that makes me still prefer the VC02s in terms of the overall tonal balance.
The mids are where the VC02s show its potential. They have the most honest mids I have ever heard. They almost don't have a signature for the mids unlike other IEMs where they have a certain way of reproducing mids. Say the GR06s' mids sound thick in every song, or the GR07s' mids are a little lacking for some guitar-oriented songs. The VC02s' mids totally depend on how a song is recorded. At first I thought they have a bit forwarded mids that guitar parts on RATM songs sound throaty and tubey which is very nice. Then I listened to The Haarp Machine and the mids were more flat instead of slightly emphasized. And then on Soilwork's album Stabbing The Drama, the mids were slightly airy and kinda soft. For my other IEMs those changes from different recordings do not seem that obvious to the extent that it may fool you to think that the way mids sound on a certain recording is the sound signature of the IEM itself.
The bass is tight and punchy and has enough weight for the songs that require it. Again, these do not belong to the "bass-enhanced" group, so bassheads that want unreasonable amount of bass, look elsewhere. The bass somewhat shares its mids characteristic in terms of versatility. It can be very fast and tight where very fast double bass drum strokes on The Faceless' album Akeldama are cleanly reproduced. But on Soilwork's The Panic Broadcast, the bass drum is more like big and slightly bloated instead of tight and clean.
To those who won't appreciate these IEMs at first, I suggest you give it some time to realize how good it is technically. With the VC02s I have effortlessly heard parts of songs that I've been giving a lot of effort to hear. I really can't get over that I bought these with their MSRP of $40 (about $37 actually). To those who love neutral, don't look back! Vsonic really defies price:performance ratio with these VC02s. This is a must-have for all audio enthusiasts.