Re: 10X12 cabinet - definitely interesting
Probably not what you are asking since I assume you want a solution with the speakers you currently have but ...
More efficient 10" or lower ohm 10" with higher ohm 12". 8 ohm 10" with a 16 ohm 12", in parallel, will get you 5.3 ohm load. 2/3 power would go to the 10", 1/3 to the 12". All else being equal, it amounts to about a 3 db bump to the 10". If the amp can do 4 ohms, it will be fine. Amp set at 8 ohms would be fine as well. It's not much of a mismatch either way. I'd probably set the selector to 8 ohms. Assuming it's a tube amp.