Lighting Is there a device to control LED intensity at will?

[G.Leave]

Is there any way to lower LED light intensity? I know this likely seems like an odd question. What I am looking for is a plug in power source with a variable control knob that would allow power output to the light.
The reason for this you may ask? My setup is very limited on vertical space(34"). I thought it would be fun to throw down a couple of heavily trained autos, but I only want to do so if I can pump some pretty intense light onto the girls to make it worthwhile in the end...with no idea how close the lights can get to the plants other than mfg's suggestions, I thought it would be much more useful to have the ability to control the flow and give them whatever they can handle.
The 2X lights I would like to get are 300w (150w real draw) rectangle panels that would be flush mounted at the top of the cab leaving enough room for airflow.

 

[BII]

Variable power supplies as you seek are common. But I would presume ability to use variable power supply would surely be model-specific; and that LEDs run off internal power supplies/circuitry, not like lights directly driven by line current. A few models have variable switches built-in.

But logically, if dimming high-power LEDs were as simple as you seek, it would be common, we'd all already by doing it.