Hey Steve,

While you certainly can load the cab with whatever you want (it is just a box after all), please take note of the following.

•The 2×12 cab is wired in series. If you wanted use 2x 16ohm speakers, you’ll want to wire them up in parallel so you get an impedance of 8ohms. In series, impedance adds while in parallel, impedance divides. You don’t want in impedance of 32ohms.
•Using these speakers, you’ll end up with a power rating of 40-50 watts. If you are planning using this with the MIG-50, you’ll want to keep the power rating at at least 50 watts unless you plan to only run it at low volumes. If you were planning on using this with a lower wattage amp, then have at.
•If you wanted to just drop in new speakers without having to worry too much about wiring and all that, a more direct replacement would be 2x 8ohm speakers with a power rating of at least 30 watts.

Hope this helps.