I've owned black line Speed-o-trons for years. The Piggy Pack system is still my favorite configuration. the main driver (1200 Ws) and three packs (2400 Ws each) gives me 8400Ws to play with! I never switch heads without powering down and waiting for ten seconds to let the caps drain before I plug in the new configuration. I also blow out the connectors and the pack sockets before I start the day's work. Dust in the pack sockets or the head plugs can cause an explosion if the plugs are not firmly connected, the spark in the gap will ignite the dust and blow the head connectors like a cannon. Never had a problem with the Speed-o-trons because I shut them down and let them drain before I plug the heads in a new configuration!