If you're trying to record or Zoom meeting (Iphone Zoom app) with a clean line-level audio into a USB-C iPhone (15–17), here's the setup Apple doesn't tell you about—but it works beautifully:
What You Need
Line-Out source (e.g., audio interface, soundboard or line-out from a sound system) - (line-out from the pulpit)
3.5mm cable (from source to where your Zoom app is running on your Iphone)
Variable attenuator (e.g., Nano Patch+ or SESMKP-27) (apple doesn't give you the ability to vary the attenuation) The Headset buddy line level audio adapter is needed for the older lightning adapter iphones.
SR-C2003 adapter cable (3.5mm TRRS to USB-C) - (this adaptor is for line-in level input)
USB-C iPhone 15–17
What to Avoid
Apple’s USB-C to 3.5mm adapter — DAC-only, output only, no analog input support. (this adapter does not work it is only for connection of a headset)
Fixed attenuators like the Headset Buddy — Only works with lightning connections (this is what I've been using for the past 4 years with my Iphone 12 before update to a new iphone).
Why This Works
USB-C iPhones accept analog input via TRRS when properly wired.
SR-C2003 cable is TRRS-compatible and routes signal correctly (supports microphone in or line-in). ( purchased mine was Sweetwater)
Variable attenuator lets you match mixer or line-out output to iPhone input level (you control the level of attenuation).
Apple doesn’t offer input gain control—this setup solves that.
Bonus TipThe Nano Patch+ or the SESMKP-27 (or similar attenuators are passive, durable, and gives you smooth rotary control over your input audio level.
Signal Chain Diagram:
source Line-out (3.5mm line-out)- 3.5 mm cable to where you're sitting) - variable attenuator - 3.5 mm cable - SR-C2003 adapter (line-in/microphone input) - Iphone15-17