A pair of 1N914 or 1N4148 diodes protect the FET input from static and high voltages. Large signals are not expected at the inputs because of the gain and limited output of around 10V P/P. Input impedance is 1M ohm to match standard scope probes. The input capacitor is 1uF 250V mylar film and output cap is 1uF 50V ceramic. The power pins are bypassed with 100uF 16V electrolytics to ground.

That’s it. Simple box, simple circuit built with parts on hand. Photos: