I'm looking for a small, sturdy practice amp for my son. He more likes to play with effects (flangers, chorus, filters, etc.) and make noise, sound fx rather than typical "playing". We've already blown through the mini amps. Will a small 10-15W combo amp w/a 6-8 inch speaker be sufficient. Other than using overpowered amps on underpowered speakers, what actually blows out speakers? I guess I'm worried about loud, low frequencies damaging the speakers. Any suggestions?

thnx