davide_bardi Hi, I have an external transformer which supplies 5v at 0.25A. I would like to know if it was enough to use the two speaker amplifiers on bela.
That wouldn't be enough: Bela itself needs about 0.5A to run and when powered from the barrel jack your power supply will also need to power Bela. You'll want to have at least 1A.
davide_bardi I have another question: is it a problem to use 4 Ohm speakers if the speaker output is 8
In practice you can do that as long as you keep the output level small enough so that your speaker doesn't use more current than specified. Namely, you should be multiplying your full-scale clipped output by 0.25.
The amp's datasheet states that the device "features an internal thermal shutdown protection mechanism". However, it gives no further explanation of this as fare as I can tell, so I wouldn't necessarily rely on it to guarantee the safe operation of the device ....
