This is a Jack tool for visual inspection of the signal chain, identification of drops in peak amplitude. For ex. if you suspect the output is low run “meterbridge -t ppm alsa_pcm:playback_1 alsa_pcm:playback_2” and compare it to the output meter in your playback application. In ppm, 1= -12dB, 4 = 0dB, 7 = +12 dB. More Jack meters can be found at Jack Meterbridge.