Yes, it's that simple. Mic to VTB1 to VF80. With an SM57/8 don't turn on the phantom power.
First, make your connections. Arm the track, push the Master and the armed Track faders up to the 0db mark, then turn your trim on the VF80 all the way down (counterclockwise). Using the VTB1's meter set on input, by turning up the gain, have your level running into the +4db zone. Then, using the output pot, have your level on the VF80 hitting just at or below the top line... No Peaking. It's that easy. On the VTB1 you have the option of dialing in tube drive. If the tube pot is set at SS, then no tube circuitry is involved. But as you rotate that pot, you dial in more and more tube "warmth". At some point you'll start noticing some distortion via the tube, but that's something some people want to be able to add, particularly to electric guitar.
It's up to you. You can run your acoustic or electric through the VTB1, or keyboard, or whatever. If you REALLY want quiet, run a Studio Projects B1 mic through the VTB1 preamp. VERY quiet. No be careful because as you get less hiss you're going to notice other background noise! Like somebody's car running next door, etc. There are ways around this...