I have a 10 watt starter pack amp and Im thinking of either getting a new, bigger one or modifing this one. Is it worth it to put in a new speaker?
what would you sudjest that would be good enough to fill up a bar, but still be afordable (i play mostly metal)? what about building one?
I don't know what you play, so no suggestions on amps go to gg&a for that. As for building on, I heard solid states are harder to build the ntube amps, and either way it wont' save you money at all.
a simple solid state wouldn't be too hard to build at all actually,

actually, it'd be alot easier to build than a tube amp. alot cheaper too. OpAmps and transistors are WAY cheaper than tube components. They're smaller, run cooler, and are simplier in terms of circuit design.

You don't get that awesome tube sound though... Plus I couldn't find a good SS schematic for a guitar amp after a few minutes of googling. That and as far as the cost for parts go... you might as well buy a brand name.
if you love the sound of you 10 watt amp, the only thing ican think off is buy a bigger amp, put a mic in front of your pee-wee amp and then put the big amp on clean, i have never done this but i know of people who have. i do not know how you would go at eliminating feedback. either that or, get a really long extetion cord and a 5 foot cable and loop it around the handle on the amp and the strap on your guitar and run around with your little amp dragging it behind you. when it blows up go buy a new amp.