Get a 'bigger' head (more watts) or add a cab — (Ampeg pf)

Add another cab.

 

Another cabinet. A PF800 into that single cabinet wouldn't gain you anything, as you're already pushing it to it's limit. You could also just replace it entirely with a 4x10.

 

add a cab, or replace with 1 or 2 "better" cabs (better=more sensitive and/ or more cone surface) 410 412 2x210 2x212 2x15 or 2x115

 

Another 210 just like the one you have would yield the most consistent results. Also, if you stack them vertically, you will get better sound in the room.

 

As you have been advised, a second identical cabinet is better than any other kind. It’s certainly way better than a 4x10. In a vertical stack dispersion in great out in the room. It’s what I use, in my case Acme, and I’d never go back to any other way of stacking them.

to address the question in the thread title, more cabs trumps more power every time! To get twice as loud you would need to increase your power by ten times!

 

Add cab.

 

Another cab, for sure

 

Add a cabinet. I have the same head. Also, going direct to the house out of the head and using the 2x10 as your stage monitor is another option if your gig spots can do that. Of course, you didn't specify the type of music you are playing. If I went back to metal or was in a Led Zep or AC/DC cover band, I'd need more headroom than I can get out of the PF-500 at 4 ohms. I've had no issues pushing this head hard. Play it until it blows up and then put down the cash to buy more power.

 

YES for the 2nd cab. It's not so much that you are getting more watts from your amp, but more importantly, you're able to move twice the air. You can always take one cab for the quieter gigs. PLUS (depending on your situation) leave a cab at the rehearsal room, the other at home, and just carry your head back and forth. Easy peasy.