I have a 6W valve guitar amp combo. It has a 8 ohm speaker out. What exactly happens if I connect to a 8 ohm cabinet? What will increase? Volume? Power of course will still be 6W, so what exactly is this for? I play in a very loud band. Mic'in my amp into the PA is not enough, so I was wondering which one would be more effective. Spending money in a more powerful combo (25W? 40W?) or just getting a bigger cabinet.