Hi Larry,
Firstly congratulations, and welcome to the family! I had a pair of UFOs that I was using as balanced mono-blocs and they were so good I got back on the waiting list for a pair of UFO25s.
On page 17 of the UFO manual there is a good description of how to wire the amps for both balanced and "regular" mono:
https://www.decwareproducts.com/_files/ugd/f1f204_e1b8a7c7f5f74930ae24a5c7b28d10...In short for balanced you jumper both - speaker terminals together and connect the + terminals to the speakers.
For single ended mono, yes you need to split the input and connect the speakers in series, as explained in the manual.
I'm curious about the Decware XLR to RCA cables, how did you get them? I don't see them on the web page and some of us have been waiting a long time for Decware to offer these.
Good luck, and let us know your results!