I agree with what he said as far as external battery.
Only other "lessons learned"... if you run a hot signal into the inputs it will brickwall, as will any device. You can turn the input gain to -15, the meters look good and you think you are golden. When you get home, it's all distorted. If you need to turn the gain down below -6 to avoid clipping on the meters, you are close. Normally this isn't a problem unless you are getting a patch from a source you can't turn down. If you are running out of your own preamp... set the gain to 0 on the MR1, and adjust the gain at your preamp.