I got the coulax cx09 about 2 weeks ago now, and my initial impressions of them aren't great, but obviously ymmv. They are the hardest iem I have in my collection, to get a good seal and are fairly uncomfortable for me. The sound is very thin with little mid or sub bass. They do have a decent soundstage and clear, defined treble as well. If you press them in your ears and hold on to them with your hands, the sound thickens up and really improves. Unfortunately, it's a pain to walk around or sit with them and hold them in your ears with your hands the whole time, lol. Again, this is my personal experience with them and I think if you can get a good seal,they greatly improve their sound and are worth the money. I won't give them another listen though, as they don't work for me. If anyone is interested in them, pm me and I'll part with them for cheap.
It's unfortunate that you're not getting a proper seal, which is absolutely vital for getting the best sound from IEMs. Have you tried using different tips?