This is going to be very difficult to replicate well, but the multiple speaker system makes sense insofar as a surround sound type effect could be created. However, the thing that seems to be missing from the equation seems to be the position of the listener(s). Right now, sound locos are not making any adjustment to even the volume alone to create any sort of scale effect sound. In other words, even in a large layout when the loco is near the engineer if might be 3-5 feet away but no more than maybe 15ft feet away when it has travelled a scale mile or two down the track. In a prototypical situation the loco might pass the observer at a hundred decibels and may be imperceptible a mile away. Most of us compensate for this by realizing that the volume on the loco's speaker is WAY too loud and is turned down to maybe 20% of its volume so that there is some fade of the sound over the limited distances on the layout.The system would need some way of detecting where the engineer/viewer is at any any given time to even think about creating scale effect sound of doppler sound effects such as another transmitter in the cab(s) that the system can detect and react to (unless one is in a static position relative to the layout, the sweet spot, which is basically how surround sound creates its effects). Not an IT guy like some on here but these are just some thoughts.