so my band is playing our first real show on new years eve. we have a PA system, but we dont have monitors. both guitarists and our bass player have multi-effects pedals so we plug directly into the mixer instead of mic'ing our amps. so my question is, can i use the amps as monitors, we've done it before using just the bass amp, but im worried our guitar amps won't be able to handle it.
Jackson RR Professional, early 90's japanese model, with EMG's

Digitech GNX3000

Crate GX 212