I've come across a MTH RK 30-2230-1 RDC Bud car set with PS2, issued in 2001. The manual says the PSA sounds can be triggered when running conventionally.
Having read about the PS2 5V issues, I'm a bit nervous about purchasing in this set as it's life could be short lived.
I may hold off until I can find a MTH RK 30-20304-1 RDC Bud car set with PS3 but I haven't found a manual for it to see if it can play the PSA sounds when running conventionally.
I run mostly TMCC and don't have DCS so if the PSA sounds of a PS3 loco require DCS to be triggered, I'll wait until I can afford both the RDC Set and DCS system.