i think mine oso got the same problem as hoho1222
my edifier h180 left side louder than the right one.
and if there is strong bass in my music I can hear like rubbing sound through my right side,making it not so clear already

I guess these earphones are given for free because it's a defective unit?
but still I like my free earphone because that happens sometimes only and it's okay most of the time.
just that sometimes got this problem
maybe because of the temperature?

No, we give out the good 1 not the defective unit, we will not give out the defective 1 to spoil Edifier brand, we r not dat silly right 
We already give few K units during the fair and it is for promotion purpose only.
For the new unit, if u purchase we will give 1 year warranty.
Sorry for the problem cause, we will report this to Edifier China.     

mr edifier...
is it the same model like previous? iirc there was edifier 800 packed some sort of a box

Yes, they repack it to English version packing.