Color has an effect on Forward voltage, smaller the wavelength(color) the more voltage it needs to "activate". Sometimes when you have LEDs with too high of a forward voltage you can drop too much voltage across the supply...
If you experiment with a RED and PURPLE led... you will see my point... the Red leds usually have a small 1.2v forward voltage, and purple may have 3v forward voltage where the Purple overpowers the red one since it requires more aka the "easy" path to ground.
The LED may be sucking more power from the speaker that you just cant hear anything.
Things to try:
- Remove the LEDs, see if your sound works without them.
- Double check power connections to EVERYTHING.
- add a resistor to the LED after the first two steps are tried.
- check your fuses
if nothing helps then idk, what other symptoms are there?