The Soundtraxx sounds good enough for me:
https://www.youtube.com/watch?v=_78JD4OsBvUvs
https://www.youtube.com/watch?v=M8RPAM5R7cYEarly steam doesn't require sophistication, it chuffs and the whistle blows.
Here is a Tsunami in an HO loco:
https://www.youtube.com/watch?v=HAiY5BBzIdQfrom my "what I did":
http://www.pacificcoastairlinerr.com/1905/decapod_sound/Steam sound is more about the speakers than the decoder sounds, "bigger is better" in the form of two dissimilar speakers and use the tender body as the sound box not one of those "sissy" canister enclosures.
Harold