Didn't try out the conrad yet,a friend of me gave it to me. I also have this behringer mini mixer:
It really sounds ok. I opened it up and it seems there is not much that could be extremly noisy like mic preamps or eqs.
But I'm also not extremly concerned with sound quality, as long as it does the job and is not extremly noisy. With these little mixers I have the feeling that there is not much that could go wrong as it's quite simple circuits.