Power Dynamics PDA-C804A User Manual page 6

Speaker connections
One or more speakers (2, 4, or 8‐Ohm) speakers can be connected to the amplifier with or without
transformers. However, before you connect any speaker to the amplifier, the total speaker
impedance must be calculated in order to avoid damage to the amplifier. A total speaker impedance
greater than 16 Ohms or less than 4 Ohms can damage your equipment. To begin with, in order to
ensure equal volume from each speaker, all connected speakers should have the same impedance.
System 1: Single speaker system
System 2: Two(or more) speakers in series