This video demonstrates Guitarix - a free Linux Rock Guitar Amplifier for jack (Jack Audio Connektion Kit) with one input and two outputs.
Guitarix is designed to get nice thrash/metal/rock/blues guitar sounds. There are controls for bass, middle, treble, gain (in/out), compressor, preamp, tube's, drive, overdrive, oversample, anti-aliase, fuzz, balance, distortion, freeverb, impulse response, vibrato, chorus, delay , crybaby(wah) and echo.
Note: guitarix has these dependencies:
ladspa-sdk gtk+-2.0 >= 2.12.0 gthread-2.0 >= 2.10 sigc++-2.0 zita-convolver zita-resampler sndfile >= 1.0.17 jack (jackd, libjack, and dev) >= 0.109.1
Seamless audio and MIDI switchover between computers