Hello. I've got beginner's questions concerning subwoofers and bass in general. I have a NAD 370 amp and CBM 170s. I don't listen to music at high volume levels; e.g., my volume control knob never goes beyond the 9:00 position and mostly it's at around 8:00. I'm thinking about getting a subwoofer, but I'm wondering if they kick in at lower volumes, or do I have to turn up the juice to activate the subwoofer. If the latter is true, then maybe they're not for me.

Also, if a speaker has a frequency range of 60hz-20khz, does this mean that tones of 40hz on a CD are absent during playback, or do you still hear something? A thank you ahead of time to anyone that may care to answer such elementary questions.