@Cheib : Great success:
I used the dtbo from an old rpi firmware (firmware-1.20181112.zip) with this md5sum:
9621a8827d53ea92e8d16e5795dd2f9a
moved the entry in /boot/config.txt (dtoverlay) before the include recalbox-config.txt and the gpu_mem entries
now I can see the hifiberry card in sound settings. 
@Cheib : Great success:
I used the dtbo from an old rpi firmware (firmware-1.20181112.zip) with this md5sum:
9621a8827d53ea92e8d16e5795dd2f9a
moved the entry in /boot/config.txt (dtoverlay) before the include recalbox-config.txt and the gpu_mem entries
now I can see the hifiberry card in sound settings.
@Zing said in Hifi-Berry / mount root:
Did you edit the information in Alsamixer/Amixer correctly?
Thanks again for your reply. I'm pretty sure I made correct modification in /boot/config.txt and /etc/asound.conf..
The issue probably lies much deeper..kernel/dmesg doesn't use the overlay for hifiberry (dtoverlay=hifiberry-dac). I don't think it gets loaded at all at boot.
There is another thread on this forum but no solution. Guess I'll have to stick with libreelec...
@Zing Thanks for your reply. I could create the file but the sound is going through HDMI nevertheless.
It doesn't seem to work with my dac light
Hello
How can I change the settings required for Hifi-berry (https://recalbox.gitbook.io/documentation/tutorials/audio/hifiberry-audio)??
Then you have to select the default sound card : just edit /etc/asound.conf (create the file if not already present) with the following content
I assume the asound.conf need to be create under (root):/etc .. However, I'm unable to create a new file with ssh and I can't mount the root partition for the rpi3 image.
I also get a lot of kernel errors and gparted
[57399.194362] debugfs: Directory 'mmcblk0' with parent 'block' already present!
[57399.548245] mmc0: cannot verify signal voltage switch
[57399.706129] blk_update_request: I/O error, dev mmcblk0, sector 2080 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[57399.962009] mmc0: cannot verify signal voltage switch
[57400.121017] blk_update_request: I/O error, dev mmcblk0, sector 6306048 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[57400.288266] mmc0: cannot verify signal voltage switch
[57400.449597] blk_update_request: I/O error, dev mmcblk0, sector 2080 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[57400.449602] Buffer I/O error on dev mmcblk0p1, logical block 4, async page read
[57400.618024] mmc0: cannot verify signal voltage switch
[57400.777688] blk_update_request: I/O error, dev mmcblk0, sector 6306048 op 0x0:(READ) flags 0x0 phys_seg 8 prio class 0
[57400.777691] Buffer I/O error on dev mmcblk0p2, logical block 256, async page read
[57400.777692] Buffer I/O error on dev mmcblk0p2, logical block 257, async page read
[57400.777693] Buffer I/O error on dev mmcblk0p2, logical block 258, async page read
[57400.777694] Buffer I/O error on dev mmcblk0p2, logical block 259, async page read
[57400.777695] Buffer I/O error on dev mmcblk0p2, logical block 260, async page read
[57400.777696] Buffer I/O error on dev mmcblk0p2, logical block 261, async page read
[57400.777696] Buffer I/O error on dev mmcblk0p2, logical block 262, async page read
[57400.777697] Buffer I/O error on dev mmcblk0p2, logical block 263, async page read
[57400.971971] blk_update_request: I/O error, dev mmcblk0, sector 28606984 op 0x0:(READ) flags 0x80700 phys_seg 63 prio class 0
[57430.170885] mmc0: cannot verify signal voltage switch
[57430.241479] blk_update_request: I/O error, dev mmcblk0, sector 28606984 op 0x0:(READ) flags 0x80700 phys_seg 63 prio class 0
[57430.600925] mmc0: cannot verify signal voltage switch
[57430.670092] blk_update_request: I/O error, dev mmcblk0, sector 29655064 op 0x0:(READ) flags 0x0 phys_seg 30 prio class 0
Error reading fat number 0
plain_io: Input/output error
Error reading fat number 1
Could not read first FAT sector
Cannot initialize '::'
mlabel: Cannot initialize drive
plain_io: Input/output error
Error reading fat number 0
plain_io: Input/output error
Error reading fat number 1
Could not read first FAT sector
Cannot initialize '::'
Unable to detect file system! Possible reasons are:
- The file system is damaged
- The file system is unknown to GParted
- There is no file system available (unformatted)
- The device entry /dev/mmcblk0p2 is missing