I may have missed it but the one thing I'd be interested in would be a battery life estimate.
Good luck.
taken from SP...
# Extremely small and compact - attaches to your keychain like a car remote.
# Uses 12 volt long life battery, included
# 50 hour battery life, depending on microphones used
# Output cable is terminated with high quality right angle male 1/8" (3.5mm) stereo goldplated miniplugs
# Available with an optional in-line level control
------
6v per? I'd like to see it pump just a little more if that's the case. Nice idea though.