This is a great product that I want to love, but it basically cant be used as a DAC for a PC user until you fix your issues.

My PC Motherboard is the Asus Crosshair x670e

Issue #1 Optical Input Issue

My brand new Fiio R7 has audio that stutters in and out constantly from the Optical In. 

I have tried mutliple optical cables - the issue is not the cable. 

I have tried the following sample rate / bit depths and all of them have issue:

44100Hz 16bit

48000Hz 16bit

88200Hz 16bit

9600Hz 16bit

192000Hza 16bit

44100Hz 24bit 

4800Hz 24bit

88200Hz 24bit

9600Hz 24bit

Issue #2 USB DAC Mode Latency

 The USB mode has significant latency across all sample rates. I can fix the latency by unplugging and replugging the USB-C cable but it comes back after leaving the USB DAC Mode. It seems that this issue can be solved when you change the sample rate, but it is the act of changing the rate that almost "resets" it to the proper latency. The moment you leave the USB DAC Screen to another mode and come back, it has bad latency again.