The solution is as cheap and easy as a line out converter from Partsexpress for less than $10. They're cheap because the circuit is so simple, just two resistors per channel. Read this if you want to understand. https://www.epanorama.net/circuits/speaker_to_line.html I used this to convert one input to an output on my integrated amp. Check out the pic to see just how simple this is. https://systems.audiogon.com/systems/8367
