The "loop" is simply a cable you (temporarily) connect from your computer's output back to the input. This will measure your sound card's frequency response, distortion etc. so it can be used for calibration purposes. This step isn't absolutely necessary but it will make your test results a little more accurate.Hi again
Im not sure at all, but so far i came to the conclusion, that:
I`ll connect my reference-mic EMC-8000 to my audiobox (dont need mic-preamp - thats build in the box).
I download the REW software to my laptop.
I connect my audiobox to my laptop (via USB).
I connect my audiobox to my hifi system (using the aux port on my hifi reciever).
To measure db i just use my smartphone SPL-meter app.
The confusion begins when I look at youtube REW guide.
One speaks about I need to make "a loop" with cables on my audiobox (that is a cable from "in to out" ports on my audiobox). Whats that about?