What do you think what is loop gain?
Our electronic definitions web site has answer for that as well:
the product of the differential voltage gain A and the feedback fraction B. The value of this product is usually very large. If you pick any point in an amplifier with a feedback path, the voltage gain starting from this point and going around the loop is the loop gain. The loop gain is usually made up of two parts: the gain of the amplifier (greater than 1) and the gain of the feedback circuit (less than I). The product of these two gains is the loop gain.