Sorry, but by themselves, level matching and blind testing won't be good enough for the objectivists, except, perhaps, as a way to determine which configuration is believed to be "tinny". There are too many ways to make mistakes and wind up with only personal opinions.
You still have to measure the signal (voltage) at the speakers to see if the "tinny" and "full" receivers actually are delivering different signals to them. Alternatively, one could measure the output of a carefully calibrated, oriented and positioned microphone, to find out if different audio is reaching the listening position, but then one also has to worry about changes in the listening environment. People moving around in the room certainly will change it.