I am afraid that those boards will not play nice in the sandbox together - at least not as supplied and without further hacks.
The Amp+ and the DAC+ board share the following pins (see here GPIO usage):
- GPIO 2 and 3 for configuration
- GPIO 28 through 31 for the sound interface
For pins 28..31 they also explicitely state that:
You can’t use them for any other purpose.
In my book this means that the two will not be able to be operated on one Pi.
Furthermore it is noteworthy that there are no stacked HATs - and the newer HiFiBerry boards share the Foundations EEPROM based configuration approach. Per Raspberry Pi Blog:
Stackable HATs featured in the specification discussion – but eventually it was thrown out due to the large increase in complexity of autoconfig and potential for user error.
So at any given time only one HAT could be connected, have its EEPROM read out, and made its information available at the device tree.
The DAC (not DAC+) on the other hand does not use any of the GPIO pins (neither EEPROM nor DAC-data) but the onboard sound connector P5. However it only works with the older Raspberry Pi models A and B - but then again the Amp+ is not going to be compatible with those.
Disclaimer: I am not using any HiFiBerry boards as of now, so this answer is based on the available documentation only.