Adrian, if your use of "ambient music" implies that your father wants to have both sets of speakers operating simultaneously to create an effect throughout the house, then no switching would be necessary. He could simply connect two sets of 8 ohm speakers in parallel to the outputs of a stereo receiver and have both sets playing. If he wants to run one set separately from the other, then a switch such as Peter described could be used, or possibly even better get a stereo receiver such as the HK3380(little over $200) which has output terminals and on/off switches for two sets of speakers.
