I am Ralf from Frankfurt, Germany.
I use Volumio on a Cubox pro. I started with RPi + Hifyberry and Volumio. I improved my setup with RPI-DAC.
I found out, that the psu is very important and than I build my own psu for the RPI-DAC. Every step brought an improvement. So I decided to design my own DAC and pcb.
I investigated the theory of DACs and digital audio and discovered a lot of myths. In short: There is no need for 24 Bit audio. It is possible to convert and save analog audio without any loss to digital audio. 16 Bit is more than you need. Just examine the math behind this.You don’t loose anything within the music when limiting it to 20kHz. A sample rate of 44kHz is more than you ever need! The thing you have to take care about is jitter and a very good psu. In my DAC I used 6 PCM1794 in parallel and a passive IV convertion.
Do not believe to get high end audio with RPi and some of these funny mini DACs (hifiberry)! But Volumio is really great!