The Line 6 is stereo and the mesa isn't. That doesn't automatically mean it won't work though. If the cab has a switch for mono just make sure the impedance (ohms) of the cab and head match. If the cab is stereo only, it's the same principle as running a full stack. If the cab is 8ohms per side then you need the amp running 4ohms with one speaker cable going to each side of the cab. Don't be surprised though, using a different cab WILL change the sound of the head at least a little.