Hey Dazz, I'm no expert but I've been mucking around with a similar project i.e chipamp and playing around with various preamps. In my findings I came across a preamp circuit called a Vibin' champ
http://www.diystompboxes.com/smfforum/index.php?topic=47371.0Gives a nice clean sound, adds a basic tone control. It's based on a fetzer valve, and has a tone control from an old fender champ. It sounds great.. Currently I'm looking at something with a bit more overdriven sound.
The chipamp that I'm using is AN7522(stereo) and AN7523(mono version). Bought these chips in an electronics hobby store in Malaysia..i think superceded, but you can still get them on ebay easy enough...originally used in TV sets. Great chip if your wanting a lot louder amp than lm386 rubyamp or similar. This thing puts out about 5w from a 12v supply, runs really cool..i don't think i will need heatsink..but will determine when i've finished everything. Tried to get it to heat up by playing it for hours, and it barely gets warm, and I live in Sumatra..where weather is hot. I just using a generic 12v 2A wallwart..so no high voltages to be concerned with.
If I plug straight into the chip power amp I get a very nice clean sound. There's no break up, or overloading..its just dull. I first tried a fuzzface directly into the amp..and it worked but it sounded dull and a little bit bass was missing when i turned one the pots (can't remember which) and the volume lowered. That experiment told me that I needed some kind of gain/recovery stage between the effect and amp..and probably some kind of buffer before the effect such as fetzer/ vibin' champ to give it a bit sparkle.
My next experiment I'm going to have a play around with more of these amp-in-a-box style circuits, with more distortion. Google "wampler black 57" or other similar from runoffgroove.com.
The other thing to remember its one thing to have everything working on a breadboard..but the complexity of the circuit for your preamp can be daunting. more parts/bells and whistles means there is gonna be a lot of work to turn this into a working amp. You will have to learn about creating a schematic, some kind of proto layout, or figure out how to layout a pcb in eagle cad, how to fabricate a pcb or how to order a pcb for fabrication. Fantastic learning excercise, .... but there's a learning curve involved in every decision for us newbs.
I'm going to try my hand at making a pcb for mine. There's trick they use here in Indonesia for doing cold toner transfer using (wait for it) ..mosquito repellent
https://www.youtube.com/watch?v=4QB1PvV0CXA&t=502s. I think theres some ingredient in the lotion that breaks down the toner (maybe alcohol or acetone or both...or it could even be the DEET they use in these products??) that allows the toner to be rubbed off the paper and deposited directly onto the blank copper board...little bit of a knack but looks pretty easy to do. Theres a few of these vids on youtube..you won't understand what the guys are saying..but you can follow pretty easily. Indonesians are ingenious little buggers, and electronics is still hugely popular hobby/occupation and basically people are poor so still repair most stuff..they can't afford the luxury of throwing away electronics when they break (like they do in my home country in Ozzie, and other places in the west like Europe and the USA).
Anyways, hope some of this helps. Give us an update of how your amp progresses.. I will do the same.
cheers
Steve