BESIGN Ground Loop Noise Isolator for Car Audio/Home Stereo System with 3.5mm Audio Cable

https://a.co/d/0bk1KfNL this is the link to the one I bought

I had the same whining noise with my Bluetooth adapter connected to the aux port. A ground loop isolator fixed that. Something like this one

This thing is working for me right now but I read it causes distortion along the audible range. (I haven't done any rigorous testing to check if the sound got changed through it) I was wondering if something like optical to RCA like the FIIO D03K would work. See if you can borrow one from a friend and check if it works. Unfortunately not, I don't know anyone who dabbles in audio.