How many Airport devices do I need to extend an existing network?

Question

Hello all,
I hope one of you might be able to help me with a problem.
I recently just moved to a different apartment, and my router (from my local internet provider) does not reach to all the rooms in the apartment.
Since I also wanted to stream wireless music in my home office I read that the Airport express would be a great solution to both extend the existing network and stream wireless from my Apple products.
I went to buy the Airport express, and asked the guy in the local authorized reseller of Apple products, if I could use this without connecting it via cables to my router (hence using it via wifi only). And he said yes, which I believed. However, after trying to set it up, and failed. I started searching for questions about my issue.
So:
Do I need two airport devices if I want to extend my existing network, when the router is in the living room, and the speakers that I want to stream from are located in my home office in the other end of the apartment? The area that I want to extend the existing network to is the bed room, next to the office.
So I thought that I could set the Airport express up in my office and connect it to the mini-jack from the speakers, and voila it would just do as I wanted to. But since I'm not a technical expert, I might have misunderstood, and I really do not want long ethernet cables running all over the place.
Is the only solution then to buy two devices? (Oh and for your information, I am not able to move the router to the office since there is no outlet for the internet, the only place it can be set up is in the living room).
Hope someone can help enlighten me on this issue. Thank you :-)

Answer 1

You need two AirPorts if you want to wirelessly "extend" the network, which will provide more wireless coverage....since both AirPorts will be broadcasting a wireless network.
You only need one AirPort Express if all that you want to do is use it for AirPlay to pick up the wireless signal and "join" your existing wireless network. In order to do this, the Express must be able to receive a good wireless signal from your router.
To test if you have a good signal, take a laptop or mobile device to the area where you want to install the AirPort Express and check to make sure that you can get a good wireless connection at that location. If you can, then the AirPort Express should work well at the same point.