Doesn't that rather suggest the preamp is doing far more than being transparent gain - and adding something special? Interesting point though.
I'm very confused with your equipment. You've chosen a very expensive, boutique microphone and a wonderful mastering grade interface.
I'm totally mystified why you'd buy such lovely equipment and appear to not really quite understand what you have? I suppose I'm perhaps wondering if you just have money to burn? A pre-amp that is in the same league as these is going to also be a niche product, with a big price ticket.
May I ask what your situation is? Do you have a sound treated studio, quality studio monitors, and a vast collection of samples and synths? Buying the capture devices at this quality level is pointless without a pair of loudspeakers capable of resolving what they capture? Please tell me you have spent money on decent monitors - because if you have not, this equipment is very lop sided and you will never hear the difference between your equipment and more conventional studio items.
This seems a very unusual choice of equipment. It is not a bad choice - but frankly a pair of loudspeakers in the same league is probably the price of a good car! You then need acoustics to support the mics - most of us do not remotely have studios where we'd hear this level of fidelity.