I use the Allo Piano 2.1 and when I use the development release I can get the 2.1 and 2.2 modes working and even select the cutoff frequency etc.
But I can not access the subwoofer volume (or rather offset from the main volume). So the subwoofer is at the same volume as the mains.
In my case the sub is way too loud. I can change this by going in via ssh and set the volume via alsamixer, but any change in the Volumio UI resets both to the same level…
Allo Piano 2.x subwoofer mode support seems to be broken at the moment. (Michelangelo stated it’l be fixed in the next version…)
Anyway the Piano board (in conjunction with a Kali board) has a real great sound if driven in Dual Mono mode.
None here in the forum has managed to get the real filtering capacity out of the 2 PCM5142 chips - because TI does not give out the software to do that unless you are - don’t know - something like a big TI customer - or god ?
The sound of the “Piano 2.x” anyway is really astonishing in “dual mono” mode - just link this to an other DSP application or an OP-amp based filter to divide it to your speakers and you will be a happy camper.
As long as TI wont give the filter design software out to us users i don’t see a great way for using the capability of the PCM5142 chips anyway - regardless of the current design bug in Volumio - which will be fixed for those who only want to build a small foot printed 2.x system…
This is another disadvantage of the PIANO PCM5142 design - as for my understanding.
Level adjustment for the “sub out” is not developed - nor planned asfaik.
I think this should be possible - if you get it managed to write a plugin. Unfortunately i’m not the one to do that…
This way i only can recommend to do the crossover by OP-amps or special extra DSPs.