What exactly is the channel stack splitter 19 years I've done this and have never heard of that particular part
The Channel Stack Splitter is used for "mixed receiver" installations or even MDU type Wally installations using a DPH42. For example, with one DPH42 multi-switch using both outputs and the necessary number of Channel Stack Splitters, one can install up to 32 Wally's in an institution of some sort, for example, like a college dorm or hospital or motel, etc.
You can't be faulted for not hearing of of the Channel Stack Splitter as it relates to Dish because MDU installs are pretty specialist installs. I got confused at first because I thought he or someone else stated "Channel Stack
Switch" and/or "Channel Stack
Multi-switch" which is a totally different piece of tech, one that DTV uses but not Dish. That is part of the great confusion of this thread, a whole lot of--well, a bit of a mess that I lost my way.
Glad the OP has things working, but this is a great example of how DBS today is far more complicated today than the early days, and one is ALWAYS best researching and even some of us on this forum can get it wrong or CONFUSED on installs and not assume DBS equipment and installs are what they were in the 1990's. I know I've been corrected for confusing things, as well, including recent changes.