Homebrew Guitar Amplifier
When my son took up the guitar, and I didn't know whether he would stick with it, I built him an amp using the preamp stage from the 100W Mark II that Nigel mentioned and teamed it with 25W kit amp using a LM2875 if I remember correctly. He is into heavy rock and he was satisfied with the sound and distortion available. Later we bought him a 40W Marshall and looking inside that, the circuit is not very different. The only advantage the Marshall has is the digital effects which he doesn't use.