Using TL081 operational amplifier, and a few electronic components can and designed a gain mitigation selector circuit.
This TL081 gain mitigation selector allows selecting gain between between +1 and -1 with a potentiometer.
The input signal is applied to both inputs of operational amplifier: the inverting input by C1 and R1, and the noninverting input via C1 and P1. Amplifier gain is R2 / R1 = 1. The signal at noninverting input is determined at the cursor position by P1. When it position is halfway the two input signals cancel each other, so do not get any signal at the output. When the cursor is located at the upper end of the potentiometer, noninverting input signal is greater than the inverting input and is gain available is at aoutput is 1 . When the cursor is at ground potential, operational amplifier works as normal inverting amplifier with unity gain. Input impedance of the circuit is about 50 k. With value of C1 on the scheme, the amplifier can handle frequencies from 30 Hz up.