REL is the subwoofer brand I most like but S/5 is more proper for home cinema applications.
If you need a sub for music, you'd better to get a REL's class AB powered subwoofer. For my taste, class D subs are not musical despite their fast transient response and high control. The problem is the lack of harmonics that make them to sound overly dry and unnatural. Unfortunately, REL class AB subwoofers are (much) more expensive than S series. Have you ever heard of Gilbratar series?