You got to get used to your machine.

"there must be a slight difference between the 2 ports"
There might be HUGE difference in how they are routed, different chips, etc.

"I wonder if there is an easy to read reference manual for those of us new to the technical aspects of playback and recording of music on Windows PCs."

There was a guide, if I remember correctly from Sweetwater, that had all kinds of tweaks for audio computers.
But I would not touch anything if it is working right smile Your computer seems to be a power horse, I don't think it needs any deep tweaking besides "High Performance" that you already have set.

About your audio "glitches", try to narrow it down to physical things. Original cable? Properly grounded AC outlet? Believe it or not, in college we lived in old house with crappy outlets, I would get all kind of noises in my recordings. Then I would move to USB settings that I mentioned in advanced power settings. Try maybe yet another port.

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Truth be told. I was a big fan of Tascam... with their US-122 about 20 years back. But when time came to upgrade, nothing was right. Crackle pop thing. So I gave up and switched to more reliable interface.