On the P100, if you play an auxiliary sound, it overrides the engine sound - once the sound is finished, the engine sound returns. This is because the unit only has a single sound generation channel.
However in most cases this will not be a problem - you will want to hear the noise.
The complexity of adding true multiple sound support would invariably add cost to the unit and make the setup and management of the unit more complex. Because it would mean a move to surface mount technology, it also means that the unit becomes a disposable item if it goes wrong or gets damaged. The P100 can be repaired if it goes wrong. It all comes down to what you want from the sound unit.
Wom
