4-Channel 2-Amp Rack Mount (1RU) System Power Supply - UL Listed. 4-channel x 2 intercom jacks, 1 program input, universal power supply. The PS-704 is a four-channel, single rack-space intercom power supply that features Clear-Com’s "fail-safe" design for maximum reliability. The power supply delivers 1.2 amps at 30 volts, supplying power for one to four channels of intercom. It will support up to 40 beltpacks, 10 speaker stations or 12 headset stations.