Hi Amra,
I'm by no means the worlds authority on pres, but i'll gladly tell you what my ears tell me about the 428!
Previously my pres were
Joe Meek twin Q pres, the 002 rack pres and a behringer desk if i was despirate to track more simultaniously. (This was to be avoided at all costs!). I wanted to get started with as many pro sounding pres as possible and the 428 seemed right for my budget.
If, like me, you've already read all the posts you can find about the 428, you'll know peoples' general oppinion.... basically that they're very good pres but not astonishing. After using them for a while I can see what they mean, but dont let this discourage you.
I ran numberous tests with various mics and sources when i first got the 428. I also recorded a section of vocal, then stacked it up by copying it across say 10/15 tracks. (Doing this helps bring out the differences between one pre and another, in a similar way that recording a whole song with one pre or another does). As a generalisation this is what i heard...
The Behringer pres are undoubtably just terrible... i have nothing else to say about these! Muddy, offensive and unpleasant.
The 002 rack pres certainly seemed useable to me for a while, but in comparison to the 428, these suddenly sound very cheap indeed. Again, generally clouded all round.
The Joe Meek pres came out pretty well... certainly useable. To my ears there's a slight cloudy low mid / high bottom thing going on and maybe a slight sibilant kind of emphasis right at the top.
Now the 428 remained clear and even, sounds musical, quite smooth and just all out more professional. The point here really is that until you hear a good pre, you dont hear the short comings of your cheap ones! I'm sure if you gave me one of these fern valve $6000 sinlgle pres my 428 may not sound so wonderful!
To say what colouring does the pre have... well i find it hard to put colours into words really, (and the impedance settings do eeek slightly different results from most mics, higher settings being brighter) suffice to say its definately not a heavily coloured pre but not clean to the point of being sterile. Just nice as an all round first step on the pro ladder pre.
If more of a coloured sound is what youre looking for you may want to look at API or Great River... although you are looking at a bit more money. Way up if you need the 4 pres or not. If i only needed 2, id probably have gone for something else but im more than happy with my 428. Now i have a base of 4 great pres its a pair of Great river next for me! lol. Hope this is of some help.