Yeah...SPL testing is probably going to be the only time you can do it, because depending on imp. rise and frequency used for the burp, the actual load seen by the amp is likely to be higher than 1 ohm //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
Otherwise, your impedance is likely to be under what the amp can safely tolerate.