Is this a decent vocal setup for SM7b?

[Wyatt W]

I am purchasing an SM7b for vocals. I will be doing a singer/songwriter set-up, just vocals and midi piano. I was looking at this setup:

Focusrite Scarlett 2i2 interface
SM7b
A-Designs P-1 Pre
I am running Reaper on Windows 7

Is this a good setup? Out of curiosity, if I only purchased the first two items and used the built-in pre in the focusrite (maybe with a cloudlifter), how much difference would there be in sound quality than using an external pre like the AD P-1? $800 worth? Enough for the casual listener to tell?

[moresound]

Go with the cloudlifter route and save yourself some money.