Hi everybody.
So, the time has come for me to buy an amp for my gigs and rehearsals (we finished our studio

).
I m playing at small clubs (50-100 people) and sometimes at venues (500 - infinity billion people). Usually DI, but I need something good and loud, 500W or more
Now, the question. Can I buy a combo and later add another speaker. I was thinking a GK combo 2x12+tweeter (500W) and later a 1x15 or another 2x12. Can I do that?
If not please suggest me a good 4x10 or 2x 212.
Thanx!