Guitarix - Guitarix is a simple Linux Rock Guitar Amplifier for https://alternativeto.
Virtual Audio Cable - Ever wanted to record your speaker output? (loopback) This is for you.
Rakarrack - Rakarrack is a richly featured multi-effects processor emulating a guitar effects pedalboard.
JACK Audio Connection Kit - JACK Audio Connection Kit|Home
ToneLib GFX - The perfect custom tone with a complete guitar studio in your computer
Loopback by RogueAmoeba - Get all the power of a high-end studio mixing board, right inside your Mac!