Testing polarity with multimeter

avo!d
avo!d Posts: 3
I have a pair of Polk RTi12's that I run in stereo, powered by an Adcom GFA-555.

I used a multimeter to test the high power signal output from the amplifier to the speakers and the readings confused me.

My test:
I tested both channels positive(+) mmeter lead to positive(+) output, and negative (-) mmeter lead to negative(-).

My results:
The right channel gives me a negative(-) reading.
The left channel gives me a positive(+) reading.

Is there something wrong with my amp? Shouldn't testing the right and left channel outputs have the same results?