正式なコメント
Typically that "new electronics" smell is flux or a cleaning solution burning-off the electronics in the first few uses after manufacturing, but after half a year, it should have already occurred. It's entirely possible that there is a component that has failed (or is failing) and thus creating the smell... it's also possible there's an overvoltage in the power supply where you have it plugged-in causing an issue with the internal voltage converter, but that would potentially affect other electronics as well, so if it's only that one PLX emitting an odour, I'd suggest you keep an eye on it, and if something fails, please contact Pioneer DJ technical support in your region to have your PLX inspected and/or serviced. If it's within a year from purchase, it would be covered by warranty.