Hey David, I remember reading your posts on this problem and I tried to make a few suggestions along the way.
Here is one more idea to think about.
In the good old days (?) I would buy a few cheap little audio adaptors like these from Radio Shack. Here is one example I clipped from Amazon. Take a look at the Answered Questions for this item.
https://www.amazon.com/Monoprice-107158-Stereo-Adaptor-Plated/dp/B003DBTAZ4
