. . . playback has started to be interrupted with frequent clicks, sputters, hiccups, and pauses . . .
Just responding to my own post (which really wasn't appropriate in this thread anyway). As my post indicated, I was pretty sure that my issues were not related to the DX3Pro, but posted just to see if anyone had some ideas about what was causing my problems. So, this additional post is mainly a FYI for anyone encountering similar issues as mine. For you computer and audio Pros, my findings are probably pretty obvious and elementary, but some of this was new (or long-forgotten) to me.
After doing some troubleshooting and experimenting, it seemed that some of my programs (namely my graphics driver's being the worst) may have been at the root of my problem. After I ran LatencyMon, I found my NVidia GeForce GTX 1070 drivers, which I continually updated by the GeForce Experience program, were causing huge (off the chart) latency issues with my PC. My PC (my bedroom PC which I use for music listening while working on my computer) is an Intel i7 4-core 6700K 4GHz CPU-based PC that I setup to be able to run Oculus VR programs about 2+ years ago, so it is no slouch. I hardly even use Oculus anymore, but these new NVidia driver updates, that I have been installing, thinking they would keep me current, seem to be increasingly very unstable and have processes that I assume run in the background and cause latency issues with frequent IRQ interrupts - thus causing pops, clicks, and dropouts in HD Audio play. I rolled-back the NVidia drivers to ver.388.59, the last stable version to be completely compatible with Oculus VR (the current drivers' version was around 454.xx?) -- and the latency toll on my PC decreased to about 1/6 of what it previously was during normal operation, and, now, never off the charts.
Anywhose, long story made short, LatencyMon may be a good diagnostic program to run on your PCs, if you are having pops, clicks, and dropouts with your PC-based HD audio. Sorry for the long OT post.
PS. And I could be wrong -- there could be other issues, but time will tell.