Adder: The IP KVM People. Experts in IP-based High Performance KVM solutions. A leading developer and manufacturer of KVM swi ... tches, video and audio extenders, KVM over IP devices and remote management solutions. Adder products empower IT professionals to manage networks and enable distributed remote control anywhere in the world. Adder video and audio extension technologies deliver high definition video and CD quality audio for many applications including digital signage. read more