I've owned them twice (gave them to friends) and I don't think they are bass-shy, just have the Ety bass signature. Actually, at $20 they are a very good deal. They are a bit bulky, and require deep ear insertion (they are true IEMs, using the term to mean they are not canalphones). Also, comfort could be a problem if you don't like either the flanges or the foamies that come with them. They do work well with Comply foamies (expensive, but very good), and you can also try the Shure soft-flex tips, which are gray and made of silicone (not to be confused with Shure olives, which are black).
Remember, you also need to replace the filter (YMMV), but you can buy them at the Ety site if you need replacements.
I gave my 616s away because I got a pair of 716s for $20 from newegg (and had them modded for another $20). The 716s require an amp, while the 616s do not.