Several things could be going on here -- I use the HD500 into my Crown XLS1000 into a single 150W Eminence Tonker 12 inch 8 ohm speaker with good results.

Unless the Pro is different than the HD500 (somebody please confirm yes or no), the XLR outs are at Mic level not line level, The line level switch on the 500 only affects the 1/4" unbalanced outputs on the HD500. The Crown XLS1000 NEEDS line level ( a hotter signal) on either its XLR or balanced 1/4" inputs to get acceptable level out of it.

The ohm load of the speaker will further drop your volume, as the XLS1000 is rated 500 watts at 2 ohms per channel, 350 watts at 4 ohms, 215 watts at 8 ohms. If you run 16 ohm speaker load on it, it will not be silent, but will be down in the dirt especially with mic level signal going in. If you have a shorted speaker or speaker lead, you would have silence, but you'd notice your Crown level meter LEDs red-lighting and shutting down the outputs. If you have an open circuit in your speaker or cabling, you would have silence, but not having the amp shut down. Also, phil_m noted that your level knobs appear to be at zero. That could also be a root cause -- you get no output with the level knobs at zero.. You should see some signal levels lighting up your LED's on the power amp when you're playing into it.

I run XLS1000 at ~100% and control the overall volume level at the HD500 output volume. I use the HD500 1/4" out set at line level to the 1/4" XLS1000 input, and set my XLS input level to ~100%.I just use a regular heavy duty guitar cord between the HD500 and the power amp input. I wish the HD500 would also push line level to the XLR outs, but they don't.

The pic of the speaker shows you have 2 inputs -- you use both and you have 16 ohm speaker load rated at 200 watts -- these are the separate speakers. If you only use one input, you have the 2 16 ohm speaker loads in parallel giving a total load of half -- or 8 ohms, that will be able to take 400 watts, but the amp will give you 215 watts at 8 ohms. You would be able to run your cab at 215 watts with one channel, or something on the order of 500 watts if you bridge your XLS1000. 16 ohms will give you 2 channels of really weak power.

Dave

Dave