I have a VTB-1 preamp and I found it's not better than the pre of my old Allen & Heath CMC-32 look for an other pre

you should also think about whetheryou are looking for clean or colored. If clean, you might want to consider the grace 101.

You also might look around on ebay for a really nice old mic pre. They're all over the place. One I'd recommend, if you can find it, is an old Ampex MX-10 tube mixer. They have 4 channels of mic pre in. They can be had for not too much money. The tubes are all still replaceable and they sound huge. there are also a lot of old reel to reel preamps that have mic pre ins that sound great. Remember, however, if you get something like this you'll need to get a phantom power supply for your condensor mics.

have fun.
cheers
ejm

If you're looking for something that will be a big difference, get a different mic.

I own the C4000b and it's a great mic for a few things, but when I want something different sounding, I go for something like my MXL V67, which sells for under $100 and sounds great on stuff that the 4000b doesn't sound great on.

Preamps will sound different from one another, but the differences are smaller than the differences you hear between different mics.