I have put together a basic recoring studio in a small room at home, it's not the best size or shape for a studio but.

Carillon computer running Cubase SX2
Edirol DA2496 soundcard+breakout box
Alesis M1Active mk2 speakers
Tfpro p3 preamp (Ted Fletcher model -£150) ?
UAD-1
Groove tube 67 microphone
Various guitars & software + midi keyboard

I am not particulary happy with my basic sound that I get from D.I. guitar & bass and mic'd vocals.
I have been pondering for ages about improvements/weak links to my sytem and if it's worthwhile changing anything. But I have come to the conclusion from reading posts & reviews that a better preamp is going to make the best improvement. The only thing is which one - I know that over a certain price I will not be able to tell the difference. I just wanted to get a few opinions before I buy, or not if thats the case - I don't want to waste money !
My ideas for preamps that will hopefully tighten, add punch & warmth over my present setup are:

TL Audio Ivory series 5060, 5051
Groove tubes the brick
Voice master pro
dbx 376

I like the SPL gainstation, but price, and will I get the best out of it ?
I hope to add a bit of presence & warmth, and I'm not worried about added colouration as I think that it can enrich a sound.

Thanks very much