Lately manufacturers have started to launch products that are able to stream music wirelessly. Streaming music wirelessly obviously simplifies the setting up of loudspeakers in a home. Without having to string wires throughout your home, you can freely distribute content into every room of your house. Using some audio transmitters, you can usually achieve a range of up to 200 feet.
The operating range of audio transmitters actually depends on your surroundings. It also depends on the frequency that is being used by the transmitter. Most transmitters in the US work either at 900 MHz or 2.4 GHz. Some devices also use the 5.8 GHz frequency band. As a rule of thumb, the higher the frequency the lower the operating range. However, there are no walls between the transmitter and speakers, devices that use higher frequencies can actually achieve higher range. That is because other devices which might interfere usually transmit at low frequencies. Also, walls will tend to absorb signals at high frequencies and therefore transmitters which are using the 5.8 GHz frequency range usually don’t have that many problems coping with interference from other devices in other rooms.
If it turns out that you cannot achieve enough range then you have several options. First of all, you can change the antenna on the transmitter. Using a directional antenna, you can focus the energy of the transmitter towards one single direction. However, note that a directional antenna is not very useful if the signal is traveling to multiple speaker locations. In that case it makes more sense to instead change the antenna on each receiver. If you are transmitting from one point to another point then you can actually change the antenna on both the transmitter and receiver to achieve maximum range.
If you still cannot get enough range then you can also use repeated devices. These devices can placed in between the transmitter and speakers. The repeater will pick up the signal coming from the transmitter and then rebroadcast it. There by range can be increased almost indefinitely. However, keep in mind that the more repeaters you have the higher the delay will be.