Just received the package.
All four foam tips are the same size and too large for me. It doesnt hurt but definitely not what I expected.
Good amount of bass, slightly less forward sounding mids than the E10, more like the C-12 in that area. Cant compare directly to the C-12 until later today.
Isolation with Foam is possibly equal to the PL50, but no doubt the PL50 is more comfortable.
Baseline: Good IEM, small starting niggles.
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@OP : Research more, if you have small ear canals like me. Cant find a tip that fits me

The stem is too damn long to insert fully and the rubber sleeve where the wire exits the earpice too long to wear over the ear using the guide FOR ME. What a shame
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Saved by a spare foam tip from my PL50. Which broke in a little while. Now on some small cylindrical silicone tips.
Sound : Bass definitely feels heavier on the C-12, but VSD1S maybe has a bit of an edge on bass texture. C-12 sounds more like the XB90EX bassy but a little shy on the mids, the VSD1S on the other hand is more like the E10 - airier mids. The E10 definitely has more bass volume than either of these.
Pro basshead? XB90EX
Rock Basshead ? C-12
Music buffet ? VSD1S
El-cheapo upgrader ? E10
El-el-cheapo upgrader ? ACH260
In short the VSD1S sounds like an E10 that has taken classical music classes - less, but more controlled bass and highs that stand out a bit better.