Not sure what you are trying to do.
Remove the code for the soundboard and just concentrate on the code for the SD card.
I have the SDcard breakput board connected to promini like this:
The constant resets are a symptom of a power problem.
There are 3v and 5v issues to sort out. Do you have a 3.3v pro mini or a 5v promini?
What are you conecting 3v - 3v? Where are you getting the 3v from? I'm not sure you can take the 3V output from a 5V promini and get enough supply current.
As I understand the adafruit SD module, it usually takes a 5v input to an onboard regulator.
The power draw when writing to the card can be fairly high, up to 100mA (or more)! That means that you must have a fairly good 3.3V power supply for the card.
Please explain more about your wiring.
I have a 3.3V promini. I connected the 3V pin on the Sd card to the VCC pin of the pro mini(3.3 V)
It still sounds like a power problem. With some promini's you can only get 150 ma in total through them.
Do you see the issue without the soundboard?
I would try to power the sd card independently from the pro mini. Make sure the grounds are connected.
I connected the soundboard with a Li battery. Soundboard is not being powered by promini.Only the Sd card is being powered by the promini.
I will try to power the Sd card seperately too and check.
SD cards need more current than the 150mA that the Promini can supply.