Where's my reverse glossary?
Part of your problem may be working with parts well beyond your level of understanding.
I originally, after high-school, went through schooling on electronics; this was a year long tech-school course.
We started out with "what is an electron" and moved from there (Grob's Basic Electronics).
Our first parts to "play with" were resistors; we spent a week or so on them. Over time we built up our knowledge; gradually with how resistors worked, how you could measure current, voltage, etc - we built our own multimeters (analog), understanding how each component (and sub-units - like the wheatstone bridge) in them worked, then calibrated them against an analog Simpson meter.
We learned about capacitors, and diodes, then transistors, and coils, and transformers - eventually getting to a point where we built and troubleshooted an AM radio (in true breadboard fashion - brass nails stuck in a foam and cardboard base, with the parts soldered between!), learning how to use o-scopes, frequency counters, etc. We learned what an amplifier was, how it worked, etc.
This led us into digital circuitry, but first we still had a bit more analog to go: we learned about op-amps, and comparators (and how one was similar to the other). Eventually we moved to digital circuits.
Resistor-transistor logic, then diode logic, etc - eventually we got to learn basic digital ICs (74xx series). Over time, we also learned about LEDs, etc. Most of us read our books, some of us subscribed to magazines (I've kept up a Nuts and Volts subscription for 20 years; I've subscribed to Servo Magazine since getting the pre-Servo robotics insert mag with my N&V), we also read books, etc.
Its a learning process, ultimately. You can't just jump in and expect to get this all figured out instantly. Nothing complex in this world works like that. Heck, I'm still learning this stuff and more every day!
So take your time; pick up a copy of the Grob book I mentioned above if you're really serious about electronics. Get some subscriptions to N&V and Servo Magazines (Make is "ok", but they don't go into as deep on theory and such like N&V and Servo does). Look into back issues (online if you can find them with Google Books) of old Popular Electronics and Radio-Electronics magazines. Continue to ask questions as well.
Finally, regarding your question: I honestly don't know if such a device exists - its probably called a line-buffer or something similar, though. It may be that the device is meant to -only- be used with a shielded cable...