Audio stream arrangement comprising: a plurality of audio devices, whereby each audio device is adapted to provide an audio stream and whereby each audio device comprises an audio device network interface for transmitting its audio stream over a network, a control device, whereby the control device is adapted to send a command over the network to any of the audio devices to set the audio device in an active state, whereby the audio device in the active state transmits its audio stream over the network, a processing device for processing the audio streams from the active audio devices, whereby the processing device comprises a processing device network interface for receiving the audio streams from the network and a mixing unit with a plurality of input channels and an output channel, whereby each input channel can be assigned to a audio stream from one active audio device and whereby the mixing unit is operable to mix the audio streams from the plurality of input channels into a common audio stream and to output the common audio stream to the output channel, whereby the audio stream arrangement is a conference system and whereby the audio devices are delegate units of the conference system, and the audio streams from the active audio devices to the processing device are transmitted by a multicast transmission, characterized in that the processing device network interface, especially the address of the processing device network interface, is in the group of a multicast transmission with a multicast address or the processing device network interface has the multicast address as its own address, whereby the audio stream arrangement is adapted to reserve a number of multicast addresses during initialization of the audio stream arrangement, whereby the number of the multicast addresses reserved are equal to the number of the input channels of the mixing device and whereby the multicast addresses are assigned to the input channels of the mixing unit 1: 1, whereby the control device is adapted to set any of the audio devices into the active state by sending a start command together with the multicast address, which is assigned to one of the input channels of the mixing unit, and whereby the control device is adapted to replace the assignment of one present active audio device to one of the input channels by another audio device by sending a stop command to the present active audio device and the start command with the multicast address of the present active audio device to the other audio device. a plurality of audio devices, whereby each audio device is adapted to provide an audio stream and whereby each audio device comprises an audio device network interface for transmitting its audio stream over a network, a control device, whereby the control device is adapted to send a command over the network to any of the audio devices to set the audio device in an active state, whereby the audio device in the active state transmits its audio stream over the network, a processing device for processing the audio streams from the active audio devices, whereby the processing device comprises a processing device network interface for receiving the audio streams from the network and a mixing unit with a plurality of input channels and an output channel, whereby each input channel can be assigned to a audio stream from one active audio device and whereby the mixing unit is operable to mix the audio streams from the plurality of input channels into a common audio stream and to output the common audio stream to the output channel, whereby the audio stream arrangement is a conference system and whereby the audio devices are delegate units of the conference system, and the audio streams from the active audio devices to the processing device are transmitted by a multicast transmission, characterized in that the processing device network interface, especially the address of the processing device network interface, is in the group of a multicast transmission with a multicast address or the processing device network interface has the multicast address as its own address, whereby the audio stream arrangement is adapted to reserve a number of multicast addresses during initialization of the audio stream arrangement, whereby the number of the multicast addresses reserved are equal to the number of the input channels of the mixing device and whereby the multicast addresses are assigned to the input channels of the mixing unit 1: 1, whereby the control device is adapted to set any of the audio devices into the active state by sending a start command together with the multicast address, which is assigned to one of the input channels of the mixing unit, and whereby the control device is adapted to replace the assignment of one present active audio device to one of the input channels by another audio device by sending a stop command to the present active audio device and the start command with the multicast address of the present active audio device to the other audio device.