It works!
I added both USB DAC modules (device_id=USB and device_id=Impacto) to the startup.sh script :
# Provide ALSA output
pactl load-module module-alsa-sink device_id=Impacto >> $PULSEAUDIO_MODULES_FILE # Impacto
pactl load-module module-alsa-sink device_id=USB >> $PULSEAUDIO_MODULES_FILE # AudioBox USB
pactl load-module module-alsa-sink >> $PULSEAUDIO_MODULES_FILE # Hdmi
now i can switch between the interfaces HDMI, USB Audio DAC and Impacto DAC via .brutefir.config:
# module and parameters to put audio
output "left", "right" {
device: "pulse" {
# server: ""; # Host to connect to
app_name: "BruteFIR 1.0o-pulse module"; # This application name
# device: "alsa_output.default"; # -> select HDMI
# device: "alsa_output.Impacto.analog-stereo"; # -> select Impacto USB Dac
device: "alsa_output.USB.analog-stereo"; # - > select Audio Box USB-DAC
stream_name: "Output of BruteFIR service";
};
sample: "S16_LE"; # sample format
channels: 2/0,1; # number of open channels / which to use
mute: false,false; # mute active on startup for each channel
´Chipfunk, you are my hero !