You really need a 'scope to double-check this. However sometimes there is a slight DC offset voltage on pins 2 and 3 from some cd (or DAC) XLR outputs. If you have a DVM with reasonable resolution you could try and measure on a low DC volts range across pins 2 and 3 and then reverse the probes and compare. This may give you an indication as to which one is "hot".
If you try this, usual dis-claimers apply! Regards, Richard