Would they sound about the same? With similar tubes and speakers, will two 1x12" AC15s being played together sound as big and as loud as one 2x12" AC30? Or is there more going on with the larger transformers of the AC30 and having 4x EL84s working together? If I'm a guitarist who mostly gigs with an AC15, but occasionally wants more headroom or volume, am I better off adding a second AC15 and going stereo, or am I better off getting the venerable AC30 (with its inherent coolness and back breaking weight)? Does the AC30 bring something more to the table other than twice the power and twice the speakers of the AC15?