Using the NE5534 low noise operational amplifier to make a very basic power amplifier. Based on the schematic from: https://cdn.instructables.com/FA3/5N1M/I1XEIXFN/FA35N1MI1XEIXFN.LARGE.jpg Note that the input connection shown in the original schematic does not make sense as it effectively shorts the AudioRight and AudioLeft signal sources together. This is likely to produce non-linear behaviour in the two sources and does not properly mix the two signals together as presumably was the original intention. This circuit illustrates the correct way to mix two signals together, using the virtual earth properties of the inverting operational amplifier configuraton on which the design is based to sum the input currents developed through RIN1 and RIN2 at the FB node. Supply decoupling omitted because in this simulation, VCC is an ideal voltage source so any decoupling capacitance has no effect. Simulation indicates that the amplifier can only swing to within about 3V of VCC and ground. Allowing for an extra Vbe drop due to each of the emitter follower output transistors, this is roughly in agreement with the datasheets: http://www.ti.com/lit/ds/symlink/ne5534.pdf http://www.onsemi.com/pub_link/Collateral/NE5534-D.PDF