I've found that even with PS/2 that powering the locomotive with DC enhances the reliability of the sound file loads. Nowadays, I power them with DC on the bench for configuration. FWIW, I power mine with a bench supply, I can monitor the precise current drawn. Even when the locomotive starts and the smoke unit fires up, I have never exceeded 1.5 amps. Obviously, I still agree with Barry, I don't want it running while loading, it's just sitting there making noise. Besides, when the sound file completes, the engine starts up, so it's your alert that it's loaded.