Bandpass audio filter in combination with PGA2311 analog ouput pins
Do I need analog audio bandpass filter on output side of this board
  and do I need buffer stage on input of this daughterboard?


The spec for the PGA2311 says that the preferred analogue signal source impedance into the device is 2kohm or less with 600 ohm as the accepted norm. The analogue inputs are single-ended and this is OK providing that the signal is single ended - if your source is differential then a differential to single ended op-amp stage would be needed.

As for the output you don't need an analogue filter on the output stage for it to perform OK. However, you may want to implement tone controls and this might be construed as an analogue filter within the scope of your question but only you know the answer to this.

Note that the output is specified as being capable of driving 600 ohm circuits