- Use either jack - Mono, 4-ohm load
- Use both jacks - Stereo, 8-ohm load
- Use both jacks - Two amp heads, each powering its own speaker (1x12)
Of course, this assumes you are using two 8-ohm speakers. Do the math if you aren't.
I mean, if you were going to make a 2x12 cabinet, why WOULDN'T you wire it this way? It uses standard Cliff-type jacks which are cheap. Real Cliff jacks are actually cheaper than a Switchcraft and give you so much more flexibility.