Personally, I think you would do better with a Shure Beta 58 with an additional foam pop filter than wasting your money with the SM 7b. What? You don't want the presence rise and all that extra proximity effect? Okay then, fix it in software.You are spending an additional $150 or more for just 2 switches basically on your microphone if you go with the SM 7b.
All of those preamp/interfaces are all transformer less inputs. You might want a preamp with any input transformer? It's a different sound from transformer less regardless of transformer less manufacturers. If you want thin and crispy go with transformer less. If you want big and fat, go for a transformer input device. And you won't find that on any FireWire interface.
Think about it
Mx. Remy Ann David