I'm switching a site off of an Avaya Partner System to a cloud FreePBX system with a Snom PA1 registered to an extension on the FreePBX.  The audio is clear when coming out of the Avaya page port, but coming out of the speaker port of the PA1, it is distorted and "buzzy."  I'm suspecting an impedance mismatch, but don't want to go changing electrical properties until I'm sure it won't blow the fairly high-end amplifier the site uses.

What troubleshooting steps should I be considering? If it turns out to be impedance, how would I verify if the unit is using 8ohm or 600ohm, and or switch?