I just purchased the SMSL P100 USB adapter as you suggested and I can't seem to get a signal from the optical or coax to work from my Android phones. I've tried using my Samsung S21 and Google Pixel 3 phones. I've tried different optical and coax cables directly (instead of using the original optical cable that I ran from the front of the car to the trunk where my Helix resides) to my Helix and no sound.
I followed your suggestions of using OTG (USB A to USB C) from the phone to the SMSL P100 and no luck. This is what I bought (Amazon.com: USB C OTG Adapter with Power, 2 in 1 USB C to USB Female with 60W PD Charging Adapter Compatible with iPad Pro, Samsung Galaxy S22/S21/S20/Note10, Google Pixel 4/4XL Google Chromecast with Google TV : Cell Phones & Accessories). I've tried using a USB A to USB C adapter that I use in my wife's car in case that Amazon adapter doesn't work.
I've tried hooking up both phones via SMSL P100 USB adapter to my home receiver's optical and coaxial input and still no sound from my home theater speakers. I don't have any apple product at the moment and could wait on an Ipad Mini 3 that I ordered for my daughter to test (but that's a week from now).
I'm almost to the point of scraping this optical setup and buying a HEC USB interface card that this guy is selling on Ebay but it's for a Helix mini. I know the rear faceplate doesn't have enough holes and won't fit but I am ok with the backside wide open until I source the correct faceplate. He is offering me $75 USD for it which is a good deal in my opinion since these optical/coax adapters are already around $30 USD.
If it work then it's worth $75 but I have no idea if it will work or not and I'll have to run a USB cable from the trunk to the front which is going to be a pain since I just finished putting all the interior panels back into my car.
Any thoughts? Thank you.
