well, 10k watts compared to 1.5-2k is like apples to oranges. i suggest upgrading the alt first because even with an added battery there is power loss. if driving to work for an hour with the system pounding the batteries will drain quick. the alt will help keep the battery(s) charged and the amp powerd correctly. then as a second upgade i suggest a battery or 2 maybe more depending on the setup.
on another note, i will be installing my alt saturday ( hope my 1/0 gauge gets here soon enough )
hn155: Rockford punch pro speakers, t400.4 deh 80prs, full audio build to come. working towards 175hp n/a, simple but fun.