...[ how to use sound cards]...

Usually, all that's necessary is to locate the output coupling
capacitors on the sound card and bridge them....

IIRC, part of the original question was something like:

"Where/How can one learn to program soundcards?"

I, too, would be interested in the answer to that question.

--Myron.
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)