Digitrax doesn't have a way to test on the programming track. I do programming on a circle of track I also use for break-in runs on new engines. I have a DPDT Center-Off switch which allows me to switch between DCC programming and regular DCC.
Some DCC sound decoders can be hard for systems to read. However, since you know which CV controls horn volume, you can just use OPS programming on your regular layout tracks.
Digitrax, bought these as donor units, had regular diesel sounds but no bell, horn etc, lights would proubly wook too is led added. At the price I paid, way cheaper than just a sound decoder.
I don't know if this is true for Soundtraxx decoders or not, but with BLI decoders when mutted the horn or whistle and bell still work.
What DCC system are you using?
This means all the regular sounds on the sound value are there, just turned off. Now for the question, I am programing on a program dedicated track, how do I test without moving to the main, or can I? Also when I tried to put in horn volume I got what looked like busy responce? New at this but have a copy of everything the S-4 sound value can do, assume this is proubly same decoder.