I have a JVC FS-Y1 Compact Component System that I use to play DVD's and CD's. It has an output for subwoofer rated at 500 mVrms/10K ohms. Does anyone know of a suitable subwoofer I could use that is not ridiculously large and fits the specs? I don't know how to choose a unit based on the mVrms and ohms. Are these measurements minimums, maximums, or what?