Welcome to the WHF forum.
I’m a bit confused by your description.  We usually describe the signal from source to speakers.   So I think you’re saying:-
iPhone 14 source > NAD C368 amplifier > KEF R3 speakers.    Is that correct?
Are you trying to avoid Bluetooth for your streaming from the iPhone?  If so, why?  If you want an alternative, I believe the NAD has a streaming capability.  Please explain what you are trying to achieve and we might be able to help.
NAD spec for reference: 
https://nadelectronics.com/product/c-368-hybrid-digital-dac-amplifier/