To stream from your iPhone to Griffin 20, you will need a wireless network. Internet access is not required. By default, the AirPort Express Base Station (AX) will broadcast an unsecured wireless network with a network name of something like Apple Network NNNNNN.
Your iPhone would need to connect to this wireless network to stream (first) to the AX. In turn, the AX would be connected directly to the Griffin 20. You would connect your speakers to the Griffin.
- Does anyone know if that's plug n play?
Basically yes. You would plug the AX directly into the Griffin 20. As mentioned above, the AX would broadcast a wireless network.
- Does the Express need to access a wi-fi since i don't have one?
The AX will provide a Wi-Fi network. Another should not be necessary.
- Does the Express need to be configured via software before using?
Unless it has been configured for another use, it shouldn't need to be configured. However, to administer the AX you would need to use the AirPort Utility. Note: You can get an AX back to its "out-of-the-box" configuration, you can perform a "factory default" reset on it.