subwoofers or not for bookshelfs?

Subwoofers work very well with bookshelf speakers that are missing the bottom two octaves, ie...20hz-80hz. Smaller bookshelf speakers (above 80hz range) require sub placement very near the speakers because some male vocals would be reproduced by the sub....not a good thing.

Dave

but many people say rel subs are best for music, so would this mean it would sound better than oem subs acoustically speaking?

To high pass the main speakers, I need a home theater pre/processor? What is good for 2 channel music?