What's the point of all this you may ask. The Raspberry Pi4 is a great product, it's small, it's compact and really capable as a player. Really a great little device.
But there is a drawback! I only have one problem with RPi4 - static white noise! I am using the official power supply from Raspberry. And boy oh boy I just cannot get rid of the noise.
Whether you're playing music or video, you can hear this hissing (sounds like running tap) in the background. I tried the analog outputs, also USB to my amp. The noise is omni present and I just cannot get rid of that static noise. To be honest it's irritating as hell and driving my insane. Hopefully I can grab a video of this noise later this weekend.
Unfortunately I don't have another 5V3A PSU to power the Pi. This is the reason for this thread, as I want to try and use POE to power the Pi and see if it can get rid of the noise. The network switch is earthed, unlike the Pi PSU (missing an earth pin) so there is a small chance this will work.
Unfortunately it'll probably take a month if not more to arrive due to the pandemic.
So last night, really out of desperation, I searched high and low for my old iFi Purifier... This device is basically a inline filter for USB cable. I'm using a standard printer USB cable for this, so I connect one end of the cable to the Pi, and the other to the Purifier. The Purifier then connects to my amp.
So what happened? The noise is gone straight away. The standard audiophile "Night & Day Difference". It's such a relief, as this was driving me insane for a while now.
There are some people who still think USB is immune from noise. Honestly do not know what planet they live on. More and more high end stuffs comes with SMPS now, apparently they are really really good. I don't know about that, all I can say is Pi PSU is really shit.