Volumio Version: all? (verified on v2.779 and current)
Hardware: RPi 3A+, Zero-W
DAC: Allo Piano 2.1
Steps to Reproduce
- Choose 2.2 mode, with an arbitrary frequency (I use 80 Hz.)
- Reboot device
- Play music
Additional Information
It seems like the main outputs are not filtered after a reboot, so my monitors get the full frequency range. (I assume the sub outputs are not filtered too, but didn’t test.)
These additional steps make it work correct:
4. Go to Settings | Playback Options and change the crossover frequency.
5. Save the DSP options.
6. Change crossover frequency again
7. Save DSP options again.
8. Play music 
After step 5 the Piano is correctly configured (just with the wrong frequency), but you can’t save without actually changing something. Hence the need for steps 6 and 7.
It seems like on boot the DSP registers are not sent to the Piano.
amixer -c 2 scontents shows the correct configuration (only the relevant part shown):
Simple mixer control ‘Dual Mode’,0
Capabilities: enum
Items: ‘None’ ‘Dual-Mono’ ‘Dual-Stereo’
Item0: ‘None’
Simple mixer control ‘Lowpass’,0
Capabilities: enum
Items: ‘60’ ‘70’ ‘80’ ‘90’ ‘100’ ‘110’ ‘120’ ‘130’ ‘140’ ‘150’ ‘160’ ‘170’ ‘180’ ‘190’ ‘200’
Item0: ‘80’
Simple mixer control ‘Subwoofer mode’,0
Capabilities: enum
Items: ‘None’ ‘2.0’ ‘2.1’ ‘2.2’
Item0: ‘2.2’