it sounds GREAT driving a 4x12, as long as you're not running the combo's speakers too. The amp has a great tone on it's own, but through the 4x12 is just sooo much better. I used an MXR ZW-44 overdrive pedal infront of the overdrive channel, and I can't imagine anyone wanting a heavier sound. The amp sounds great on it's own w/o the 4x12 btw, just better with. And if you're worried about volume......don't! This thing can get very loud! Especially through 4x12's! Hope that help's out