different sounding m8's topic

So i have my girlfriends m8 here, a golden one , and my gun metal m8. My problem is that the speakers sound completely different. The m8 of my GF has no bass at all, its actually a little louder on high frequencies, its squshing in my ears. But it sounds thinner and not so full as my m8 does. I dont know if there are different versions of m8's but she is all set up because she thinks my m8 sounds better.

I did take off the speaker-covers. I heated them up and slowly lifted them because i thought there is dust under the covers. But there is nothing. Everything clean.

So hers is sounding thinner and higher-pitched. And mine are rich full with more bass.

What do you guys think