I acknowledge that there already is a topic that is still discussing this issue while it's already been marked as solved, and I like to think that the Soundcloud staff doesn't bother to look into it anymore because of that. I hope this gives the problem a new shot to be fixed. Sorry if I'm making wrong assumptions.
Matter of fact is, the playback quality is really bad. Even for 128kb/s it's giving me artifacts that do not appear when I render my stuff at 128kb/s from my DAW. Pretty everything has already been said here, the topic is more than a year old and the last post is from about an hour ago, which is pretty ridiculous for an audio streaming platform:
Just to make sure there's also a suggestion and not only complaining in here: Switch to .opus which has significantly better quality at even the same bitrate.