Well...I am not certain that DC is needed. I have heard AC amps with no hum. I would also suggest that making that much DC will have challenges all its own, and perhaps divert resources from other parts. It's also a noise risk itself, with multiple paths wo sneak in noise.it's an interesting challenge, and I don't feel qualified to say what should be done. Matter of fact, it's your amp, work it out, and learn a lot along the way, and then build another...:)
cheers,
Douglas