You’ll need either five or seven speakers plus an active (powered) subwoofer, then another 2 or 4 speakers if you want compatibility with Dolby Atmos.
There are entry-level 5.1 speaker packages available which have the subwoofer and five small satellite speakers all in one box. These are a great way to get started if you are on a budget. Higher end packages are also available and are a good option if you would like smaller speakers and music reproduction is less of a priority.
To get the best performance, especially if your home cinema will double as your HiFi, you should consider a set of full sized HiFi speakers. A HiFi 5.1 package usually consists of two floor-standing speakers for the front, a pair of bookshelf (or stand-mount) speakers for the rears, and a centre speaker and sub-woofer which is designed to match the set. An extra matching pair of speakers can be added to make it up to a 7.1 system. This type of package will give you the best sound performance for both music and films.
If floor-standing speakers would be too big or obtrusive for your room, consider downsizing to a pair of stand-mount speakers for the front left and right.
If you are trying to design your room in a very minimalistic way and don’t like the idea of having speakers on show then it might be worth considering installation speakers. These can be built into the walls and ceilings of your room and are covered by a magnetically attached grille. The grilles on installation speakers can usually be painted to match the colour of your wall or ceiling.
If you want compatibility with the latest 3D surround sound such as Dolby Atmos, you’ll also need an extra 2 or 4 speakers to do this. These can be installed in the ceiling, which looks the neatest and gives the best performance. If you aren’t able to cut holes into your ceiling for the speakers, consider instead using a pair of specially designed Dolby ATMOS speakers. These are small wedge shaped units with the actual speaker driver on top. They project the sound upwards and bounce it off the ceiling and can be positioned either on top of the front left & right HiFi speakers, or on a shelf or piece of furniture.
Whether you go for a small satellite package, HiFi speakers or install speakers, as a general rule it is best to choose a manufacturer which specialises in just making speakers. Many of the larger electronics manufactures make speakers too, but they are usually below the standard of what you’d get for the same price from a specialist manufacturer.
Dedicated speaker manufactures tend to have highly enthusiastic research and development teams made up of obsessive audiophiles. More detailed information on HiFi speakers can be found in the HiFi and audio guide.