Welcome back! For the UE600, the 1More Triple Driver IEM would be a worthy replacement. For the Monster Turbine Pro Gold, I think the Massdrop x Noble Audio X would be a decent replacement. BTW, IIRC, the UE900s is a bit more forward in the mids than the TF10 was. So it's direct descendant, but I wouldn't necessarily call it a direct replacement.
12/28/16 at 8:14pm