I'm building a battery-powered boombox and plan to use HiFiBerry Amp2 with a Raspberry Pi 3B along with a 20 Ah powerbank that has USB-C Power Delivery (either 12V/3A, 15V/3A or 20V/3.25A). In order to get the correct voltage from the powerbank I've ordered a USB-C PD to DC adapter, such as the ZY12PDN.
Now, I've read that the ZY12PDN momentarily outputs 5 V to the DC output until the correct voltage has been communicated using I2C, and then switches over to the selected voltage.
Is this a problem for the Amp2? I get that the device (probably?) won't boot until a valid supply voltage (12 V - 20 V) is actually supplied, but I just want to make sure that nothing gets damaged by supplying 5 V to the DC input of the Amp2.
Bonus question - I plan to use both channels for an active 2-way speaker where the crossover is running in the RPi. Woofer on one channel and tweeter on the other channel. The datasheet says that I can output 2x30 W, but what happens when the woofer wants more power than the tweeter? Are the outputs able to output e.g. 55 W + 5 W instead of 2x30 W?