Wiring details

Power to the Raspberry Pi is supplied via the Hifiberry amp. The PiTFT gets it's power via the Raspberry Pi.

Pin layout

First thing to do was to connect both the hifiberry amp and and pitft to the same raspberry. They are designed to run exclusively on top of a raspberry, but they use different pins, except for the 5V power pin. The diagram shows which pins are used by each board. Only the 5V power is used by both boards. Luckily the Raspberry Pi has two 5v sources, so pin 2 is connected to the Hifiberry Amp, and pin 4 to the PiTFT.

Wiring

After wiring them carefully with jumper cables I managed to run them simultaneously.