Tell us about yourself!
Power is going into the amp. The amp is then powering the pi. So, the only safe way to power the pi is via the micro USB port (you could direct wire into the GPIO's but that has no regulators for voltage or current spikes).
What power supply do you use and where do you get your speakers?
Programmable Fiber Optic Fairy Wings
Apple pie mochi doughnuts(gluten free)
Beer Bottle Lock