We use 2 Yamaha DXR 12 tops and a DSR15 sub for all our pub gigs and any events up to 150 people.
It's plenty loud enough for us with everything going through it, but we're a loud acoustic band with a controlled drummer, so perhaps a full on rock band would need more.
Having said that, I use the same rig with an additional DSR15 sub for a small festival stage and it copes with the rockier stuff without protesting, but only just...