Sorry to be hard on you guys, but as hackers I know you can take it. 
Indeed we can!
Ive' been an EE for over 25 years designing HPC as well as analog sensor systems including some AA designs over the years.. We EEs often get too theoretical, and less pragmatic about construction. I apologize for my comment; there is a lot of practical knowledge here learned by many hard knocks.
No apology needed. In my experience, there are not many of us EEs with both theoretical info and practical construction experience, even fewer left that have *analog* design experience, and even fewer with *power electronics* design experience; and of that few remaining number, remarkably few who are guitar/bass players and hackers. I designed power supplies for a living for some years, and I learned to learn from my technicians. They may not have sat through the theory, but they'd seen a lot of smoke.
My concerns we're due to comments like designing a power supply before the amplifier. As an engineer this sounds silly. Pragmatically, ICs are a cheap date so use what PS stuff is on the shelf. I now get it.
Quite a lot of the "power supplies first" comments originated with me, in other forums. I've advised audio builders/hackers on the internet since the days of usenet, before the concepts of the world wide web. I found that many builders of audio amps sweated bullets over the abstractions of the latest supersymmetrical hyper-doozie power amp schematic, then were astounded to find that the power supply cost more and was far bigger and heavier than the amps, no matter how complicated. I deliberately tried for a short, succinct, dash-of-water-in-the-face that would get junior-apprentice audio builders to pull their heads up (or out! 8-) )
That idea may sound silly perhaps; but more importantly to me, it's startling enough to get someone to think about power supplies. And actually, in today's electronics world, the idea that a power amp is primarily a power supply with a little circuitry grafted on to let some of the power out is factually correct. Back when getting a power amp to run at all and spending the equivalent of a couple hundred of today's dollars on output transistors was a challenge, there was some justification for leaving the power supply last. But today, even if you're going to do a discrete amplifier, the power amp circuitry is going to be a trivial amount of both the cost and the complexity. It's going to come out to be about 3-6 square inches of PCB coated with parts, and power transistors stuck on a heat sink. Period.
About ten minutes in the Mouser Electronics catalog will get you all the parts except the PCB. But the enclosure, the power transformer, the filter caps, the heat sink, those are going to be hard to find and expensive. Power transformers have not seen the kind of decline in prices that power transistors have!
I was extruded through formal project management training in my last job. One of the tenets there is to put the effort where the difficulty, cost and complexity are. By concentrating early on the difficulties of powering your new 50kW amplifier, you'll be less disappointed than you would be if you built the amps and found out that the power supply can't be had for love or money.
And there's the idea of maximum upgradablility. If one has decided to build a 200W amp, then the power going into the load is defined. You know ahead of time what that is. From there, one can decide what efficiency they can practically get. A little reading in Duncan, Self, Slone, or the ones they got the theory from will show you that the efficiency of the amp divided into the output power tells you immediately both what DC power you need to provide the amp and also what power has to be dissipated in the form of heat from the amplifier, clarifying a couple of big, critical practical problems. If you don't get solutions to those problems - DC power, heat, and efficiency - you cannot and will not have a working power amplifier no matter what goes on the PCBs. But if you have a suitable power supply for a say, 200W class AB amplifier, then no matter what amplifier circuit you tag onto it, you'll have a 200w amplifier. You can upgrade the power amp circuitry and outputs much more easily than you can upgrade the power supply. Chip amps, discretes, hyper-customized solid-platinum and germanium amps, anything will go in there if you have the power supply, enclosure and heat sinking right and use the same output power and class.
Looked at from the standpoint of practical building, the amplifier is almost an afterthought. The amplifier almost does not matter.
It is **exactly** that line of reasoning that led me to buy that 100W Rogue guitar amp. I had no idea that it would be a good amplifier on its own. But if it put out 100W into two speakers (and likely 4 ohms load from that) then I already knew what the power supply was inside it. If the power transformer was not burned out and it had a suitable heat sink, it was worth the money to have a body to plant a better brain in. $40 was cheaper than I could buy a similar power transformer.
Anyway, it's a good idea to think of things from different viewpoints. In this case, IMHO building gets easier if you view amplifiers from a mechanics- and power-supply-centric viewpoint. It leads to some different and I think useful results.
Sorry to have been so hard on you. You're neither the troll nor the tyro that it sounded like at first read.
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