You have to be specific. Do you want a 5W amplifier or a 5000W amplifier? Are you concerned about hi-fi quality? How much experience do you have building circuits? Having a schematic isn't the key to building things like this, you need to have experience in component selection and circuit layout.
I would check out the various projects posted on www.diyaudio.com
I have worked on many circuits i just was in a hurry when i was posting, no i'am not worried about hi-fi quility and i want a 5 to 10w amp schematic just because i have a working amp but not perfect yet.