Is XLR to USB okay?

Mic preamps bring the low mic level up to line level. There are some usb mics out that work without an out board preamp or converter.

Rocky

Preamps, as the name implies, is an amplifier.  In the case of a microphone, a preamp applies amplification of the very small electrical signal produced by a microphone diaphram and raises that signal to something that can drive a line input.  That line-level  signal can then be used by other other music equipment - ie., an EQ, or a line input into a convertor, or into your montior amp.  That monitor amplifier raises the level again so that it can drive the speakers that you can then hear.  Your ears are kind of an amplifier, taking the incoming sound wave, which causes vibrations on your ear drum which is then picked up by the cillia in your ear and turned into electrical vibrations that your mind interprets.  Think of it as the circle of hearing -  going from air vibrations to the mic to electricity and then back to air and then electrical brain signals.

Ahhh!! Thanks, AT- that makes tons of sense. I guess the big thing I couldn't get is that a preamp IS AN amp, not just a stage prior to amplification. I'll have to check the etymology of 'preamp', though.