In my car I have an amp with 600watt output and subs but just bought speakers with 700watt output. Do I need a bigger amp? or is there something else I should do?
I presume you mean your amp has a 600 watt output and the speakers are rated to 700 watts? No problem, the amp will drive them- you don't need a bigger amp, and the one you have probably doesn't really run at anything near 600w anyway, that'll just be it's absolute peak figure.