Guitarix is a virtual guitar amplifier for Linux running with Jack.

It takes the signal from your guitar as any real amp would do: as a mono-signal
from your sound card. Your tone is processed by a main amp and a rack-section.
Both can be routed separately and deliver a processed stereo-signal via Jack.
You may fill the rack with effects from more than 25 built-in modules spanning
from a simple noise-gate to brain-slashing modulation-fx like flanger, phaser or
auto-wah, or you can also select plug-ins from the large list of LADSPA and LV2
plug-ins.

WWW: https://sourceforge.net/projects/guitarix/