bowtie, your the last person I would argue with but if there is a difference listening to the speakers than the signal is different, even if by a minuscule amount.
If we can "listen to galaxies" light years away, I would think that something that we could actually hear could be measured. We may not "understand" what we have measured, that part I can agree on. But I'm sure that the "difference" could be isolated.
Timber would be a slight shift in the frequency at certain points or the intensity of the frequency. That is easily measured.

BillWojo