Like Sean said, more speakers will get the most out of your Pro Jr. A pair of 12's (or more) would make a big difference.

Elevating it up on an amph stand would help get the sound out better too so that it's not blasting past your knees.

I've found it tough to warm up a SS amph to any serious degree.

Another thought is that micing it through the PA and monitors is a generally good solution if you have an open channel for it.