[LAU] comparing audio recordings on the command-line?

Hi, I'd like to compare recording quality of portable recorders. I only care about the line-in input of these portable recorders. I'm thinking: * play audio through a good DAC and feed the line-in of each recorder * copy audio files off the SD cards from the recorders * level match the inputs. Probably based on "sox FILE -n stats" output change input levels on each recorder to match levels. * play audio again through the DAC and feed the line-ins * copy audio files off the SD cards from the recorders again * run something like diff(1) for audio I'm willing to look at a spectrogram/graph image with feh(1), but I _really_ don't want to touch a mouse or tab through form buttons/boxes/inputs on a GUI. Thanks for reading.