The Protech Audio Model 702 group of switching mixers, are designed for use by audio professionals. Each unit is carefully designed and constructed to provide highly reliable, quiet switching of audio signals, to an on-board output, and a link output. The unit may be used to control paging systems, provide signal routing in broadcast facilities, or sound system configuration in live venues. Each Model 702 unit is configured as a two input switched mixer card. Different input combinations (mic or line) are available as outlined in the architect's and engineer's specifications portion of this engineering data sheet. The 702 cards are linkable, allowing larger systems to be configured. By applying ground to the individual channel control pins, each input channel may be assigned to the on-board output, or the link out. The on-board output is balanced, transformer-isolated. The output is designed to drive 600-15K ohm loads. The link output for each input channel has a separate switch from the on-board output switch. This feature allows the input channel signal to be assigned to the link output, or the on-board output, separately.