我的工作設置RPi3 B+使用 Raspbian，Chromium 瀏覽器的聲音直接傳送到ALSA環回設備（由核心模組啟用modprobe snd-aloop）透過此 Chromium 參數：--alsa-output-device='plug:front'。整個命令：
/usr/lib/chromium-browser/chromium-browser --ignore-autoplay-restrictions --disk-cache-size=50000000 --kiosk --disable-extensions --noerrdialogs --allow-insecure-localhost --enable-gpu-rasterization --enable-zero-copy --enable-native-gpu-memory-buffers --alsa-output-device='plug:front' https://youtu.be/nW--BbY6Z5E
PS：plug:front取自aplay -L輸出。
該聲音已成功從 Loopback 捕獲設備錄製/hw:0,1捕獲達克採這是現場音訊串流。這裡只是相關部分/etc/darkice.cfg:
[input]
device = hw:0,1 # soundcard device for the audio input
sampleRate = 44100 # other settings have crackling audo, esp. 44100
bitsPerSample = 16 # bits per sample. try 16
channel = 2 # channels. 1 = mono, 2 = stereo
但我還需要透過連接到線路輸出（插孔）的外部揚聲器播放此聲音。
這怎麼做得到呢？你能幫助我嗎？如何克隆聲音輸出？
# uname -a
Linux rpi3 4.19.114-v7+ #1303 SMP Tue Apr 7 15:44:16 BST 2020 armv7l GNU/Linux
# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
Subdevices: 7/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 0: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 1: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
Subdevices: 7/7
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
card 1: ALSA [bcm2835 ALSA], device 1: bcm2835 IEC958/HDMI [bcm2835 IEC958/HDMI]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: ALSA [bcm2835 ALSA], device 2: bcm2835 IEC958/HDMI1 [bcm2835 IEC958/HDMI1]
Subdevices: 1/1
Subdevice #0: subdevice #0
# cat /proc/asound/cards
0 [Loopback ]: Loopback - Loopback
Loopback 1
1 [ALSA ]: bcm2835_alsa - bcm2835 ALSA
bcm2835 ALSA