I was looking closely at the sub bass plugs and wondering how they actually work since they are hard and not a soft porous material for sound to travel through.. I realized is how they work is they actually likely prevent the dynamic drivers movement. If you look at the different pieces they are different lengths beyond the flange point. Kind of like packing a sealed subwoofer with foam, they work the same way. They block the amount of air flow making it tighter.
That said, I really love these IEM's. The soundstage is slightly small but the detail and clarity is just beyond me. I'm going to email FLC and see about getting the original cable because I hate this stock cable.. I've tried the silver upgrade and I hate it. It sounds better but it is horrible. Its my opinion anyways.
This IEM really is the best buy for the money as far as audio goes. Headphones, IEM's, speakers, anything. They are amazing. Nay, astonishing. They tickle my ear buttons every single time I listen to them. Unlike mother other high end IEM's that can either blow your mind or suck depending on the source and more specifically the song, these shine no matter what I throw at them.