Say I have a 75 watt (solid-state) combo amp. If I add a 4x10 cab, how much will the volume actually increase? Will I have a 75w volume 12" speaker as well as four 75w volume 10" speakers, or will it just make one steady 75w volume 5 speaker stack? Basically, will it sound like 150w or more if I add that 4x10 cab? Also, does this apply just as well to bass amps?