Hi Nick
At least there is plenty of room in HO Loco's for sound
I'm just about to do a sound install in one of my Favourite Loco's , mind you I don't have the decoder yet
and I'm out of Isolated backplates as well , but I do have a few ESU speakers to play with
I just wonder whether to hook them up 2 in series or 2 in parallel
Regards Zmil