Thank you Leo for sending the DAC, I greatly enjoyed the Apple Pi.
Here are some thoughts. I tested the unit against Sony HAP-Z1S, OPPP 205 and a chinese ES9038PRO balanced DAC.
Speakers: B&W 804S and JBL 4312B
Amplifiers: Hypex NC500 monoblocks (SparkoS class opamp and factory buffer), Lexicon RV-8 (analog pass-through)
Speaker wire: AudioQuest CV8
Source PC: MacBook pro
Here are my initial impressions
The build quality is top notch and I really like the layout.
The unit sound great out of box, very organic, almost neutral and full bodied (compared to ES9038PRO based DACs). The vocals were amazing especially on the JBL 4312B monitors.
The bass sounded bit lean. My experience has been without the right XLR interconnects for Hypex amps, the bass is a hit or miss.
Green PCB would have made the unit gel more nicely with the Raspberry Pi, but I understand using red color as a product differentiator.
My only concern and probably you might get it from many people is the mini XLR connector. I have some very high end XLR interconnect cables that I have found to match very well the amps I use, having the mini XLR connector limits the option.
Its a great value for building something under $200. Selling it as a kit with nice case would be ideal and something that user might prefer.