Anyway I did some testing yesterday and if you use this overlay everything works fine.
https://raw.githubusercontent.com/eragefe/Rockpi-S/master/armbian-5.9.y-kernel.dts
and with both cards
https://raw.githubusercontent.com/eragefe/Rockpi-S/master/armbian-5.9.y-both-cards.dts
Welcome to Armbian 20.11 Focal with Linux 5.9.10-rockchip64
System load: 4% Up time: 0 min
Memory usage: 33% of 213M IP: 192.168.1.138
CPU temp: 34°C Usage of /: 6% of 15G
[ Menu-driven system configuration (beta): sudo apt update && sudo apt install armbian-config ]
Last login: Thu Dec 3 02:15:34 2020 from 192.168.1.100
root@rockpi-s:~# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: rockchiprk3308a [rockchip,rk3308-acodec], device 0: ff320000.i2s-rk3308-hifi rk3308-hifi-0 [ff320000.i2s-rk3308-hifi rk3308-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: SimpleDAC [SimpleDAC], device 0: ff300000.i2s-pcm5102a-hifi pcm5102a-hifi-0 [ff300000.i2s-pcm5102a-hifi pcm5102a-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
root@rockpi-s:~# speaker-test -c2 -D plughw:1
speaker-test 1.2.2
Playback device is plughw:1
Stream parameters are 48000Hz, S16_LE, 2 channels
Using 16 octaves of pink noise
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 128 to 131072
Period size range from 64 to 65536
Using max buffer size 131072
Periods = 4
was set period_size = 32768
was set buffer_size = 131072
0 - Front Left
1 - Front Right
Time per period = 2.776536
0 - Front Left
1 - Front Right
Time per period = 5.460972
0 - Front Left
^C 1 - Front Right
Time per period = 0.830656
root@rockpi-s:~# speaker-test -c2 -D plughw:0
speaker-test 1.2.2
Playback device is plughw:0
Stream parameters are 48000Hz, S16_LE, 2 channels
Using 16 octaves of pink noise
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 128 to 131072
Period size range from 64 to 65536
Using max buffer size 131072
Periods = 4
was set period_size = 32768
was set buffer_size = 131072
0 - Front Left
1 - Front Right
Time per period = 2.749659
0 - Front Left
1 - Front Right
^CTime per period = 4.607317
root@rockpi-s:~#