I have a 12V NRG varalux on camera light which I often use as an eyelight. Am I likely to get any problems (audio interference?) if I run it off an AC to 12V adapter? Anything I should watch out for when buying an adapter?
Try to get a filtered power supply - a slight flicker possibilty exists with the "multivibrator" types of dc supplies.
And, of course, be sure that the output of the supply is adequate for the amperage of the light(s).
I used a set-up like that years ago, with up to four 25w. Cool-Lux heads off a 200w. filtered DC supply. Additionaly, I punched four holes in the case, disconnected the barrier teminals in front and added four fused 4-pin XLR connectors. Sort of like a power supply for an original Dedolight.
The biggest problem will be with the the cable - too much of a run from light to power supply could put too much resistance on the connection. I used coiled communications cable, 12/2/shielded/ - 7'extended/3'retracted on each fixture with no more than 10' of extention ( 12/2 straight, shielded w/xlr-4's on each end) per light. The shielding may have a purpose such as grounding to the power supply if you wire it that way and it may reduce r.f. -- I just used it because it was available and had the right sized internal cable.