Just a few impressions after a hearing test

Mainly I do hearing test with SHURE SRH550DJ headphones, and normally I consume music with M-Audio HCS-9920MK2 full size speakers via JVC AX330 amp.

I'm comparing my design to chinese module based on the same PCM5102 chip

To do (almost) blind test I connect two sources at the same time and switch between them with single button on the amp. 

Sound is quite similar, however

- Mine gives a bit claener feeling in whole range, meaning a bit cleaner bass, mids and highs.

- Scene is slightly better with mine

- Most importantly, noise pickup is much better on my board, which was my biggest concern, and here is why.

Biggest issue with Orange PIs I had so far is that  they are quite considerably noisier than Paspberry PIs. With yellow module above Orange PI out of the box is quite unbearable, picking up all kind of noises when you perform any activity on the board, in other words all the time. This was the biggest motivation for running my own design. 

I'm not much experienced on that matter and all I did is 

- Provide whole ground plane between Orange Pi and DAC

- Provided independant low noise stabilized power for DAC

- Try to lay out board carefully, all caps close to consumers, no overlapping paths and this kind of things.

Guess  that did the trick. Although one  just might ask himself, why wouldn't you just start with Raspberry Pi in the first place ;-)