Originally Posted by bassman2011
I wasn't sure how a 4 ohm amp works with one 8 ohm cab. Does it reduce the wattage or does a 4 ohm amp need to be connected to a 4 ohm cab in order to get its full wattage?
Well, yes and yes. With a solid state amp (versus a tube power section, which behaves differently), the amp will deliver more power to the speaker(s) as the nomimal impedance of the speaker(2) is reduced.
So, your amp will put out less power with your single 8ohm cab than it would with two 8ohm cabs (which results in a 4ohm load). The only thing you can do wrong is operate that 4ohm minimum amp below 4ohms (e.g., hooking up three cabs, or two 4ohm cabs, or a 4ohm cab and an 8ohm cab).
In your case, using one of your 8ohm cabs or both of your 8ohm cabs is fine with that head.