I've read your previous post about this. I don't own any of the software you are talking about, so I can't directly answer the question.
If you suspect a System Volume conflict, like one program "stealing" system volume from the other or something, you can switch JRiver MC to use it's own Internal Volume, which is independent of System Volume.
Tools > Options > Audio > Volume > Volume Mode
Otherwise, maybe if you describe the problem you've seen and how to reproduce it, we might be able to give you more advice.
Good luck.
Brian.