Volumio/Piano2.1 interface questions

Hi there,
As I mentioned in my Introduction post, I am doing more advances work with the miniDSP portion of the Allo Piano2.1 board.

My questions asking for clarification

Under what conditions does Volumino have to re-boot with the Piano 2.1 DAC and why? From my use, I know it has to reboot when changing DAC modes say 2.0 to 2.1 or 2.1 to 2.2.
Why does the system NOT have to reboot when changing crossover between the 2 PCM 5142 - say from 70 to 80 Hz? When I do change the crossover to say 80Hz I know that the high pass filter coefficients in the main 5142 must be updated, and a similar process for the low pass filter in the sub 5142. That has to be done either by re-loading firmware for 80Hz into both miniDSPs, or by writing the new filter coefficients over I2C control bus. Can someone explain that process? I notice when I do change the crossover frequency, Volumio mutes the main speakers, but strangely does NOT mute the sub. Since I infer that the reason for muting is to update the firmware, it causes concern that the firmware in the sub 5142 is not getting updated, potentially allowing it to incorrectly operate off a different crossover frequency. I can go through with a room measurement scan but this is some effort as I have to get calibrated - but if needed will do so.

Many thanks for assistance in advance.

You may want to make a reference to this question in the DAC section for Allo to answer.