Hey just played last nite and noticed that my volume was significantly lower than normal. The only thing I did that was a little different from my usual practice set up was add a cab. I usually use my V4B with one Ampeg SVT 210 HE and its fairly loud with great clean volume. But last nite I added an extra 210 HE. I plugged both cabs in to the 4ohm jacks, both hooked up directly to the amp, it was QUIET and broke up fairly quick. During a break in the set I unplugged one cab and ran just one cab through the 8 ohm output and this brought up the volume significantly with a great increase in clean volume. Any idea why this is happening?? Could it be that the 100 watts isn't enough to drive both cabs?? Or could it be an issue with the head??