I have an old MRC diesel sound decoder in an HO Proto2K SD50. While the sound quality is not superb, it runs very well as long as I keep my track clean (much better after I powered much of the track via power buses). I was went from no sound to this one engine and I LOVED it.
I have a new Broadway Ltd. AC6000 with Quantum Sound - the quality of the sound is MUCH better and you can control the volume (big advantage). I can't access all functions via my MRC Prodigy but plan to go with Prodigy Advanced once the railroad's budget looks good enough.
I love MRC's simple handheld stuff and the price is good. I'm anxious to try a Brilliance decoder but the cost is steep for stinky diesels - steam is another beast and I can't comment on that.
Problematic speaker installation can make any decoder sound terrible - did you feel like you got a good install on the speaker? Tight fitting . . . sealed space behind the speaker . . . reasonable pathway for the sound to escape, etc?
