My father bought a Sinclair Z12 and was going to clone it and make a stereo amplifier, but in the end he used a Mullard 10W design with OC28s as output transistors and I think OC16s as drivers. He still has the Z12 unused and I copied the circuit diagram down a few months ago with the intention of building a pair when I have time.
Dave
GW7ONS
www.parcgwyn.talktalk.net