This program makes a linux computer equipped with a modern sound card behave as a traditional hi-fi preamp, but able also to make advanced DSP equalization and crossover tasks.

That means that, with a proper soundcard, external sources can be used, be them analog or digital, along with digital libraries or streamed sources.

codeberg.org/rripio/pre.di.c
github.com/rripio/pre.di.c