Yep, (looking at the MkI sled) the orange wire is the amp remote turn on. Red is power (to accessory or constant, depending on how you use the empeg) and black is ground.

Don't forget the ground on the RCAs (ground by the amp, IIRC)

Also, give the contacts in the connectors a periodical cleaning with alcohol and Q-tips or something similar - they have a tendency to build up crud that lead to poor contact and crackling.

/Michael