You should have plenty of power at the power amp. 2400 watts at 2 ohms is roughly equal to 1200 watts at 4 ohms and 600 watts at 8 ohms. The power ratings are usually reflective of an impending meltdown level which doesn't reflect real stage conditions, but when you're playing you're not just cranking out a full level continuous sine wave either, so the amp not working at the edge.
Your cables should be fine too. I wouldn't sweat the power cord. Hopefully whoever manufactured the speakon cables used reasonable gauge wire, but at these short runs, it doesn't matter that much either. Bigger in both cases is better but probably won't fix the problem.
What you do want to watch for is to make sure the preamp is not overdriving your poweramp. QSC has a sort of odd setup that should work fine but doesn't work the way it looks. Most of the QSC amps have a set of LED level/clip indicators and input gain knobs on the front panel, but the controls don't match the indicators! The LEDs are showing OUTPUT level clipping, so when that top LED flicks on, you're generating full output power. There's no visual indicator on these amps for when you're overdriving the power amp front end and QSC amps have slightly higher sensitivity than most (e.g. generate full power at slightly lower signal input level) too.
I think the way that you can find the right settings for the input gain knobs on the QSC would be to set the volume level of your f1-x pretty high (maybe 3 o'clock), set the input gain on the power amp pretty low (maybe 9 o'clock), the play hard and slowly increase the power amp gain until it doesn't sound clean anymore. Obviously, this can be pretty loud, and you have to try to determine the difference between the speakers distorting from too much input power and the power amp distorting from too much input signal. But with an 8 ohm cab, and being somewhat gentle, you shouldn't be endangering the speaker too much.
The input gain level where you start developing overload is the max you can run the power amp cleanly - more than that and the preamp output will overdrive the power amp. You won't get more volume, just more distortion. Because the sensitivity is high, you may find that the max input gain is at 12 o'clock or even lower. You're still developing the full power that this amp can make, even if it looks like it's only turned up half way.
Now, when you want to adjust your stage volume level, do it with the preamp volume instead of the power amp input gain. Then you'll always have a clean signal. You can also turn the input gain down on the QSC, just don't turn it up past the max point you determined.
Not having an input level clip indicator on the QSC seems like a bit of a boner. The traditional setup in the old days would be to turn the input gains to the max and control the volume with the preamp knob, but because of the sensitivity, it difficult to control the preamp volume without crossing into the distortion zone. It's easy to claim that QSC was playing specsmanship (if you set the amp up this way, it will be producing full power with the input gains at half for most signal sources and that makes the amp look more powerful than one where the input gains are cranked to generate the same level, but in the QSC case, that additional gain is not usable). That may be the case, but there's no real standards on these levels, so who's to say?
When you turn up the bass knob on the preamp it will REALLY increase the power level that you're asking the amp for. Your ears perceive volume logarithmically which means that things that sound twice as loud take 10x the power. Crank the bass knob and you can go from asking for 100w from the amp to 1000w very easily.
The watts thing is kind of kooky these days too; again, a game of specsmanship. The power supply in a QSC amp is a switching supply that operates a Class H amp. Unlike an old-school Class AB amp with transformer power supply, modern amps like the QSC can generate enormous transient power but can't dissapate the heat of driving these levels continuously. So, the really high power ratings are a bit of a fallacy. The power supply of an old Crown DC-300A is slightly less than 50% efficient, but within that design spec, the power supply and output transformers can crank out the 250-300watt for days at a time. The power supply of a QSC is probably 90% efficient and can make a real burst of 2400 watts, but if you tried to sustain that probably even for seconds the entire thing would melt down. Building a 2400 watt traditional amp would require 4800 watts of AC in which is more than your electric oven uses even when fed at 240v! Again, this isn't a fraud - although you probably come as close to a high level sine wave as anything out there, your continuous levels are much lower.
I think you'll probably be able to realize a great increase in clarity when you get the input gain situation cleaned up. That may be enough to get you fixed up. If the clean output level isn't high enough, then I think you would want to try that second cab. Increasing the cabinets sucks from a hauling standpoint but is probably the only way to really fix the problem.
David Fung
