Thanks everyone for all the help. I've managed to not damage anything and the two different cabs sound really good together.

Both cabs are 16 ohms. It would seem that since the amp reads "2 x 16 ohms" I should be ok. Why do you say both cabs can be 8 ohms when the back of the amp doesn't provide for that option?

The two speaker outputs have the following written below them:

"1 x 8 ohms or 1 x 16 ohms or 2 x 16 ohms (minimum total impedance 8 ohms) speaker outputs are wired in parallel"

I have a Orange CR 120 head. I have been using an Orange PPC212 (closed back) cab. Today I stumbled into a used Orange PPC212-OB cab that was almost free. I want to run the CR120 head through both cabs at once. The head has two output jacks so, do I simply run speaker cables from the head to both ca...

Is the volume on your daughter's bass turned up? If the volume on the instrument is all the way off, your won't hear anything.