jacostilllives said:
what i was always told was if you are turning the master past 50% you need more watts. Adding another cab will make you seem louder. Is your gain turned up? How many watts is your amp? We need more info.
Old wives tail about where the master knob is.
No relationship between master knob level and how close you are to maxing out the power amp.
You can misadjust the input gain too low to where you need to run the master wide open and still not drive the amp to full power. Have something in the effects loop (compressor?), if it has more than unity gain, you could end up having to turn the master DOWN below 30% to keep the amp from delivering full power. Play light fingerstyle, master at 50%, maybe you're way under full power. Switch to slap/pop, and suddenly you're getting peaks at full power, master still at 50%.
The knobs all control GAIN, not POWER OUTPUT. Power output depends on total gain and how much signal input there is.
If you hear distortion, check your stuff. If the amp has way more watts available than the cab handles, probably need more cab. If the speaker handles many more watts than the amp puts out, you need more watts more than you need more cabs. In either case, you may ultimately need more of BOTH, cab and amp. In your case, your weak link is power, since your cab can handle way more power than the amp is capable of putting out.
If your amp is 250W@ 8 ohms, its liable to be only around 160-175 watts @ 8 ohms. That's not a lot of watts if you guys are loud. The speaker handles 350W@ 8 ohms, so shoot for an amp that puts out around 700W@8 ohms, so you have power plus some headroom. Then if you still need more volume, you can add another 8 ohm 350W cab, the amp will put out around 1000W@ 4 ohms, or 500w per cab, so you'll still have some headroom when you're running 2 cabs. Going from 175W to 700W gives you about 6dB more volume. Alternately, getting another speaker now instead of an amp nets you around a 6dB increase also, between a bit more power from 4 ohmm load and the extra cab providing more speaker area. So its a tossup which way you go first. Ultimately you will probably want to get both, more power and the 2nd speaker. Which you get first is up to you. I like more power, easier to carry than an extra cab.
Doubling your power adds 3dB to the output, which does NOT sound twice as loud. Far from it. That's why people end up with ridiculously large amps for bass. It requires crazy increases in power to double apparent volume. 10dB increase (10 times the power) sounds twice as loud. Its ultimately a losing battle beyond a certain point.
Randy
That's what I was afraid of. 
