I don't remember where I found this, but it made a lot of sense so I saved it. See if you can imagine which SCA pre's would fit in his categories:
[quoted text]
When you spend a lot of time on a lot of different amplifiers, you learn what they are good for. The most important thing is where a given amplifier will naturally place something in a mix. EVERY preamp out there will put your stuff in a different place, so you can save your self a lot of headache when it comes time to mix if you are thinking ahead to where you want things to go when you are tracking.
For example-
amp a might have a really forward present sound to it. track your leads or melodic guitar overdubs
amp b might have a scoop out of the midrange. track your rhythm guitars
amp c might have a very defined and rooted bottom end with a sublte top. track your entire drum kit
amd d might have a clear bottom with a very open top. track your vocals
what do you get from this?
before you apply any EQ, you will have a drum kit that is the furthest thing back in your mix and your kick drums will be the thing that is the most "grounded" in the bottom. You'll have rhythm guitars that sit tucked in behind the lead guitars. You'll have a vocal that doesnt need to be hipassed which will sit on top of the mix unobstructed.
If you were to track every instrument through the same preamp, every single thing you track will be fighting for exactly the same space in the mix. Imagine for the sake of argument the extreme example of the pre you choose only passes 100hz to 2K. Think of how much EQ you are going to have to add to the kick and bass to get it below the mix. think of how much eq you are going to have to add to the top to get it to sit above everything else... This can be logically extended to other amps.
There is creedence to using different preamps. IF you chose not to and use just one amp, like you said, records were made like that forever so you are hardly shooting yourself in the foot or anything, but it is certainly not bullshit when people talk about using so and so for this and so and so for that and its easily provable over the course of a quick session, people that knock this simply havent tried it, the effect is entirely obvious.
At any rate, which ever you chose, you will develop a style and you'll find something that works for you. Everyone is so different in their approach, I know for instance, I have the absolute HARDEST time making tube amps work with solid state amps. Seems silly, but I hate mixing stuff that was recorded with both, makes no sense to me. Im very much in the minority with that though.
What might give you some food for thought, forget about mic pres and just consider amplifiers in general. I recently built an 1176, had an 0-12 on the input which I changed to a 31267 and the entire performance of the 1176 changed and turned on a dime. It went from sticking stuff on top to rooting things to the bottom. If you built a transformerless version Im sure in comparison it would float in the air above everything. One version might be good for drums, one maybe better for vocals, one maybe better for guitars and they are all essentially the same circuit. Its really a discussion about dimension, using different amplifiers is the shortest and most direct path to getting dimension and space into your mix in a way that you will never ever ever achieve using EQ on all the same amplifier.