A-BUS 4 Hub - 1 in 4 out with Power Supply -uses 1 to 4 AB1 Keypads 

Four-Room A-BUS® Expansion Hub

With the ABH 4, no room in the house need be without music, no matter which AVR is in use. For existing systems linked to A-BUS® Ready products, the ABH 4 allows you to power up to four rooms, or even more with additional ABH 4 hubs. For systems without an A-BUS Ready jack, the ABH 4’s onboard audio inputs add the simplicity of A-BUS technology to any multichannel or stereo receiver with a "Tape" or "Multiroom" output; you can even use it directly with a CD or DVD player or outboard tuner to bring music to any room.