I just purchased Sony Shelf system CMT-HPZ9. I failed to note the small words "Micro Hi-Fi Componet System", CMT-HPZ9. 170 total watts rms. I unpacked it, but not yet installed. I thought I was buying a Stereo. Sooo, (1)would someone explain the difference between Hi-Fi and Stereo on shelf systems? (2)Is one preferred over the other? (3)Any comments on this system would be appreciated. Thanks!