Missing low frequency tones from bluetooth audio output
Assuming you meant to put a 1MΩ resistor on the output, your filters are flat across the audio band and shouldn't be affecting your audio.

Also, you can simulate the AC response of filters in LTSpice with the .ac simulation command, like so:



This gives you a nice plot (I plotted from 1Hz to 100kHz):



Which shows the frequency response is completely flat.

However, if that series capacitor is reduced to 1uF to match your schematic, you lose a little bit of low-end, but the -3dB point is still below 20Hz (i.e. it's not a significant amount).