Determine wattage and ohm ratings of your amplifier. All amplifiers have a minimum speaker ohm requirement that must be met to avoid damaging the amp. Typical amplifier ohm ratings are 8 and 16, with some amps capable of handling 4 ohms. Wattage usually increases as ohm levels decrease, and this can be a dangerous situation for most amplifiers, especially tube models.
Determine the wattage, or power-handling capacity, and the ohm capacity of each speaker cabinet. If multiple speakers are enclosed, the ohm rating can be changed somewhat by rewiring the speakers using a speaker wiring chart. Total power capacity is determined by figuring the combined wattage of all cabinets. It is not altered or determined by speaker ohms.
Plug the first cabinet into the amplifier's speaker output with a quality speaker cable.
Using more speaker cable, plug the second speaker cabinet into the first cabinet's additional speaker jack. This manner of connection is called "series," and will divide the total ohm rating by the number of cabinets. For example, two eight-ohm speaker cabinets wired in series will cause the ohm rating to change to four-ohms. The total ohm rating must match the minimum ohm rating of the amplifier.
Turn on the amplifier and test for operation.