has anyone tried that subwoofer that's available from Subaru? how does it sound? i have the so-called premium sound system now, and i don't want to tear apart the car replacing it. i like to listen to my tunes loud, but right now the regular speakers begin distorting once you hit about 34 to 36 on the volume level. however, when i turn down the bass in the EQ, the sound does not distort when i push it louder. the sub has an integrated amp, so if i keep the bass low on the head unit EQ, it should still provide enough bass output for my taste. i'm not looking for loud bass, i just want to be able to turn up my stereo loud and get proportionate clarity from the bass.