Unfortunately, that is appearing to be more and more the case. Sad. Here is my ordeal if you haven't already read about it. I too have a volume (loudness) mismatch as well.
Sorry to hear that, but at least we know we're not alone!
But I feel like I'm especially unlucky, 3 out of 5 chinese earbuds I've bought have build issues! This is a very bad percentage in my opinion.
- ve monk plus - no problems
- diy nickhck mx500 - no problems
- FAAEAL Datura Pro - the drivers just popped out and stopped working
- MrZ Tomahawk - drivers became loose, I was able to super glue it back before it stopped working.
- LBBS - 1 side treble is broken