Bookshelf speakers provide great sound  but can be a bit complex to set up at first. They enable you to listen to great music from any source - analog vinyl to full-digital. Most quality bookshelf speakers have a “two-way” design - a two-way speaker that  includes two drivers: a tweeter and a midrange/bass driver (also called a woofer. More drivers mean more quality sound, basically.

Most of us normally prefer a flat frequency sound, sound that is balanced and neutral - that means you don't perceive the high pitch or the ultra boom bass. Everything in balance. 

Tip: Do not put each bookshelf speaker in tight corners, or on top of shelves. Put them out in the open, give them space - especially between it and the walls. This helps the extra bass come out perfectly from the back. Also, put the tweeters at ear level.

The best bookshelf speakers for stereos: ELAC Debut B6 Bookshelf Speakers (from veteran speaker designer Andrew Jones, almost like listening to live music in your room, can easily be upgraded to a surround-sound system)
The second best bookshelf speakers for stereos: DALI ZENSOR 1 (Better looking than ELAC debut, also more expensive, same sound quality, more compact)
The best upgrade for bookshelf speakers for stereos: KEF Q100 (more expensive than above two option, but very good sound performance)
The best affordable bookshelf speakers: Pioneer SP-BS22-LR (also from veteran speaker designer Andrew Jones)