I have found speed matching can be interesting. I have two locos with Soundtraxx decoders. One is a K4 Pacific, large wheels, and a 2-8-8-2 with small wheels. After some work and research, I found that Soundtraxx does not support CV5 and 6. Instead, Soundtraxx uses CV 23 and 24 to do the same. But it does help to use JMRI Decoder Pro for this process. This makes it so much easier.
I am still trying to figure out how to get the two running at the same speed. They do run the same at startup, but as I accelerate, the faster loco in front, pulls ahead. Adjusting CV2 helped the startup ssue. Now to figure out the speed table. They say it is pretty simple. Guess I don't have a simple enough mind! LOL But I will keep trying.
Will keep working at it. Do the same.
Ted