I have been a fan of Train Control Systems (TCSDCC.com) decoders for many years.
TCS has only had one Largescale decoder for many years called G8. Been using them in my engines and can says they are rock solid.
http://tcsdcc.com/Customer_Content/Products/Decoders/G-Scale/G%20Series.htm
Now TCS will be introducing two new Largescale Decoders (WOW501), one for Steam and Diesel in September. 2015.
http://tcsdcc.com/Customer_Content/Customer_Info/Whats_New/What’s_New.htm (Go to bottom of the page)
If you never heard one of these new sound/decoders before you will be surprised. I took one of the WOW121 Steam decoders and installed it in a Bachmann Largescale Forney engine with a large speaker. It turns heads at shows when people hear it and all the possibilities these decoders have in sound files. The sounds are real recordings loaded onto a micro SD card and can be removed if needed.
I do not know right now what Steam or Diesel engines will be available for the WOW501’s but hope it will be narrow gauge steam engines. They did announce this was going to be available in HO this month
Dennis in Tennessee