What type of signal is coming from a 3.5mm audio plug?
or does it create only AC voltage (without standing DC) (for example, alternating from +100mV to -100mV) ?
(when referred to the 'ground' wire on the 3.5mm plug which is the thickest connection, closest to the wire itself).
If it's only AC without standing DC on it, then how come the TEA2025B microchip can work fine when connecting it directly to the input pin?
because that would mean the input pin would have no problems with negative voltages applied to it... (with the negative voltages, I mean something like -100mV, coming from the AC input signal).