Can you plug a combo amp into a 4x12 cabinet?

Your amp only puts out 30W max at 4 ohms. No matter what, to run a 4x12 cabinet, you're going to need more power. My suggestion is to set up a master/slave system. You'll need a mini stack; one cabinet and a head (two cabinets and a head make a full stack). Use your Vox as the master, and connect a cable from the headphone jack to the input of the head. If you can find a head that has the option for a master/slave set up (look at the back for inputs and outputs), even better; you would just plug into the slave jack of the head. Those heads will let you bypass their preamp, and just use the amplifier portion of the circuitry. If not, just set the head for the mini-stack to clean and use the regular input. You can get a good mini-stack for $500-600 that will give you a 4x12 cabinet, and a head that will put out about 100W; Marshall, Crate, Line 6, and Ibanez. Hope that helps.

Vox 4x12