Added the 3S2P LiPo battery pack from recycled laptop battery (see my other project). It is connected to the amplifier board through an XT60 connector and a switch is placed on the power cable.
The playback time at full charge looks to be around 6h, even though very volume dependent. After that the power is cut by the protection board of the battery pack, but just one of the three pack is discharged. Need to replace the faulty pack in order to boost the battery duration.