audio interface

I just need to know if the circuit itself is going to work, because I'm currently not able to simulate it and I need confidence to continue with the PCB design. It is a simple audio interface for a guitar, it consists of a preamp (Hi-Z), the codec (PCM2900C), and an amplified output with a...

Hi there A bit of an electronics novice here, forgive the lack of knowledge. But I'm trying to record my voice to my laptop via a USB-powered audio interface (it has USB cable for both power and data). A low hum has appeared which gets worse if I touch my mic body, and almost goes away...