Citation:
Q. If I am using just one speaker cabinet, can I still use the Hot Plate if it has a different
impedance than my speaker cabinet?
A. ONLY if the impedance of the speakers is equal to or greater than the amplifier, AND
the impedance of the Hot Plate is equal to or greater than the amp. Again, this will lessen
the effectiveness of the Hot Plate’s tone controls.
From the manual ...