Methods for a very low gain audio amplifier?
A low-count buffer amp might consist of a class AB emitter follower:






simulate this circuit &ndash; Schematic created using CircuitLab

Q2, a NPN general-purpose transistor will run a bit warmer than the lower PNP transistor. Something that can dissipate a bit more heat like TIP29 or MJE180 might be more robust.
C1 will be an electrolytic capacitor of greater than 6v rating, with positive end facing the two transistor emitters.
Note that this buffer depends on your instrumentation amplifier to provide +3v bias - "input" must be connected directly to op-amp output.