I figured out himedia player can only bitstream FLAC file that have sample rate larger than 48kHz (i.e. 96, 88.2, 192...); For FLAC file that have sample rate below 48kHz, (i.e. 44.1kHz) Q10 pro decoded and all become 48kHz (as shown in my AVR) and music volume can still be adjusted by Q10 pro remote.