Hey Scott,
Thanks a million, mate. wink
For once in my life, I've elected to make things reasonably simple on myself and have gone with a kit-set approach.
Jaycar down this way make a pretty good 50 Watt Mono amplifier that is based upon an LM 3876T chip.
(In case you folks were wondering, 50 Watts is more than any amount for a Bass amplifier, anyone that tells you any different, is trying to sell you something you don't really need)
I've bought all the bits for it (sans speakers) and I was having a wee bit of a set-out session here the other night.
This kit requires a dual-rail power supply of +/- 35V and for this I needed a centre-tapped transformer, the only one I could find was a toroidal type and unfortunately, it takes up half the case.

Here's a little picture of how far I've got so far:

[Linked Image from i89.photobucket.com]

When Labour weekend hits here the weekend after next, I'm going to be into this like a rabid dog.
Not so much the electronics construction, but building the speaker cabinet that will hold 4 x 8" speakers and a base port.
These speakers are rated at 200W a piece (RMS) and from the specs, they should do the trick.

One thing I was wondering about though, do you need to have a pre-amp to have any sort of "tone shaping" with an amplifier, what I mean is (very loosely), Treble, Mid-range and Bass pots.
A bass guitar gives you rather limited control over how your signal sounds on the output of an amp.
Is there a simple circuit I could use, to effect some sort of top-end or low-end cut/boost?