I wish I could buy a HumX but I live in Europe and it’s not available here.If you can DIY, try the circuit below, use a 0,01uF 600V capacitor and two diode rated 15A 600V or higher:
https://i1.wp.com/circuitcellar.com/wp-content/uploads/2015/08/Novacek301-4.jpg?w=371&ssl=1
For RCA cables, try a transformer like the Jensen:
https://www.jensen-transformers.com/product/ci-2rr/