Looking for the perfect in-ear headphones EP 630 is my currently last candidate. Tested with my iRiver IHP 120 or 890 IFP I've different models of Sennheiser MX series, and Koss The Plug, and the Sony EX 71SL. I love lots of bass, has long been the Koss my favorite, provided he sat perfectly in the ear. However, I found him in the long run as uncomfortable in the ear. As initially written, is currently the EP 630 my favorite. He has a good sound, good bass for me and sits well in the ear. The only drawback to Koss is that the environment will notice a little more of the music. Compared to Sony EX 71SL he offer a little more bass and not quite as dominant heights.