I updated the guitarix package in the audinux repository to the version 0.46.0, to have the NAM IA model loader.
Then I made a test using the last TuxGuitar-1.6.3 too.
The first test: without a NAM model. Just using standard Guitarix plugins:
Then, I used a NAM model downloaded from tone hunter: https://tonehunt.org/
The model Marshall_JCM_800_2203 was used (JCM800 2203 - P5 B5 M5 T5 MV7 G9 - AZG - 700.nam) and a TubeScreamer from Guitarix.
I needed to increase the pipewire-jack buffer size to 256 to avoid Xruns.