OK, time to attempt to ask the question that's been rattling around in my brain for a little while - when is one cab not enough? Specifically, I have an Ashdown ABM600 and a Barefaced Two10S. This will likely do for most of the gigs I'll play, as they're mostly in pubs, working men's clubs, sports clubs, etc. but there's a nagging thought that says "you might need another one if you play anywhere bigger". Is that thought correct? Chances are at larger venues I'll be able to DI into the in-house PA so will only need to worry about hearing myself on stage, but at what point does doubling up on cabs become a necessity, and should I rely on venue PA being good enough? I'm conscious that my amp is realistically 500W @ 4 ohms into the Barefaced, but if I double up it'll only be c.450W @ 6 ohms with 2 x 12 ohm cabs. So less power but more speaker area - does that equal louder, better dispersion, people at the back being able to hear, or does it just equate to a waste of several hundred pounds for no benefit? If it were to become a necessity would I need to get a more powerful amp able get the full power from the speakers?
Apologies for the lack of technical terms and vague ramblings, I'm just not quite sure how to express what I'm asking.