Anyway some pages from the Wiki can be useful
Please refer to the current implementations at:
https://github.com/rripio/pre.di.c
https://github.com/AudioHumLab/pe.audio.sys
FIRtro es un paquete de software de tipo 'black box' para filtrar y ecualizar altavoces activos, también para ecualización de sala (DRC). Dispone de funciones de preamplificador como control de volumen calibrable con Loudness ISO 226:2003, y selección de fuentes analógicas y digitales (locales o remotas).
FIRtro is a "black box" software package, intended to filter and to equalise active loudspeakers. Also intended to perform digital room correction. FIRtro has preamplifier capabilities such a calibratable volume control with Loudness ISO 226:2003 compensation, and a customizable input selector for analog and digital (local or remote) sources.