|Since I still can't concieve of what you are trying to do based on your description, I just threw out a guess that sounded like it might work.|
I kinda get the impression you're trying to re-invent the wheel here when the problem already seems to have been solved.
"If you connect your existing parallel cable to the DB25 end of the other cable and connect to USB port" (2 cables, NO?)
I fail to see any difference between using two cables that don't seem to work and using an adapter and a Cable that (supposedly) work.
I'm left to assume your goal is to do away with the adapter, rather than get the thing to print.
Maybe I'm missing something. No offense intended but the "Twilight Zone" theme just clicked on in my brain. ?????
There is nothing to learn from someone who already agrees with you.