Guitarix - Guitarix is a simple Linux Rock Guitar Amplifier for https://alternativeto.
Mixxx - The most powerful free DJ software in the world.
GNUitar - GNUitar is guitar effects software that allows you to use your PC as guitar processor.
Zulu DJ Software - Zulu DJ Software is the best tool for singers and musicians.
Ampire - State Space Modeled guitar amp/cab/stompbox simulator.
VJ6 - If blending music is your essential thought process, you might need to search somewhere else for your DJ blending software.