well...what you need to do is make shure you have a bass amp and a guitar amp. Do not run both guitars on one amp or it will sound like **** hitting the wall. Try to buy a 30 watt amp,that should cut it. As for a bass amp your friend could get a 15 watt amp it should be loud because the bass has more bass than a guitar so bass amps dont need to be that loud unless your playing a big place.

hope this helps