[Jack-Devel] Volume much softer on Jack than on ALSA/PulseAudio?

I'm running an ALSA -> PulseAudio -> Jack bridge setup on an Ubuntu 18.04 x86 laptop. Sound played via ALSA directly seems to be much louder than via Jack, eg.: gst-launch-1.0 audiotestsrc freq=200 volume=1.0 ! alsasink is much louder than gst-launch-1.0 audiotestsrc freq=200 volume=1.0 ! jackaudiosink I've looked at every volume knob I can find (via alsamixer, qasmixer, pactl list, etc.), and they're all at 100%. Does the PulseAudio -> Jack bridge have a volume parameter hidden in a config file, or something like that? Thanks.