I have used the SRPP principle in a stereo headphone amplifier. The circuit below was made twice (lefthand and righthand channel) and combined with a PSU it forms the amplifier. Allthough the output impedance of the SRPP amp does not exactly match the headphones impedance, the amplifier provides a nice and clear sound to my Sennheiser headphones.
The input comes from a digital source (CD-player, DVD-player or PC soundcard).
Circuit diagram, 1 channel
Building in progress, spring 2012