With the 420R I/V resistors at 5V supply voltage, output is measured at about 1.3V RMS with a 0dB sine wave. That is1.84V peak to peak. Consumer 0dBV is 1.414V Ref level. That is +2.28dB. Not sure about the calculation.
Hardware: RPi Zero W | Allo Kali | ProtoDAC TDA1387 X8 | PGA2311 | Icepower 500ASP | Harbeth SHL5
Software: Moode 8.3.3
Source: Win 10 NAS
Software: Moode 8.3.3
Source: Win 10 NAS