I did everything you guys told me to, in triplicate, so I suspected a computer problem. I called a computer geek in the area and he went over the obvious things that were already done, such as checking the headphones and cable, re-installing a sound card, listening to another fully panned song, reinstalling windows 10, etc. He still didn't believe that I thoroughly covered all the bases and wanted to check for himself, because if what I said was true, that could only mean a hardware malfunction. And that would be exceedingly rare, especially on a Dell that was less than a year old. I didn't want to pay him to re-check what I already did. Anyway, he suggested that I talk to his friend, another computer geek who was also a musician. We covered the same things, and he came to the same conclusion. Then I borrowed another computer, and from there on everything completely changed. All I did was insert the SD and when I called up each song they played in perfect stereo with the panning exactly as I adjusted it. What a blessing!