I'm using a hiby fc4 amp with my lg phone. It's it usb c which i don't know works on iphone. It puts out a clean 4v balanced 4.4mm to my car dsp. I have nothing to compare it to but it was cheap and effective. It gets warm and draws power from the phone.

Thanks for the ad, Mods. I'm very much a beginner compared to most on here. Happy to learn from others and offer my own experiences. Cheers