Input capacitor on audio MAX49XX
I'm not familiar with those devices but reading the datasheet suggests that the capacitors are only required if the previous stage has a DC offset. 

The MAX49XX is unusual in that with only a positive supply it will pass an audio signal with voltages above Vcc - 5.5. That means that if you supply it with 3.3 V it can pass signals from 3.3 - 5.5 = -2.2 V to +3.3 V. If your audio signal is within that range then no capacitors are required.

If you do need DC blocking then you select a cut off frequency well below the lowest required audio frequency. The capacitor value is given by $$ C = \frac {1}{2 \pi R f} $$ where R is the load resistor (headphones?) and f is the cut-off frequency.

If your load is low impedance then you're probably going to need to use an electrolytic capacitor due to the high value capacitor required.