Hyperpixel4 and HDMI audio

Hi, I have just installed piCorePlayer with HDMI audio output, wich worked fine. After that I mounted a hyperpixel4 display, and manually install the driver. After boot the display works well, but the HDMI audio doesn’t initialized.

The relevant part of the config.txt:

hdmi_drive=2
hdmi_force_hotplug=1
hdmi_force_edid_audio=1
dtoverlay=hyperpixel4
overscan_left=0
overscan_right=0
overscan_top=0
overscan_bottom=0
enable_dpi_lcd=1
display_default_lcd=1
display_rotate=3
dpi_group=2
dpi_mode=87
dpi_output_format=0x7f216
hdmi_timings=480 0 10 16 59 800 0 15 113 15 0 0 0 60 0 32000000 6

The boot log part:

Waiting for sound card b1 to populate… Failed to find b1… Done (42).

Can I force the HDMI audio with Hyperpixel4?

Thanks!