Tascam DR-05 Stereo Portable Digital Recorder Built-in omni-directional microphones Stereo mini headphone jack for external stereo microphones (provides plug-in power) / External line input Tempo change (VSA) function for adjusting the speed from 0.5 to 1.5 times (in 0.1 increments) Chromatic tuner, Powered by 2 AA batteries, USB power or optional AC adapter (Tascam PS-P515U), MicroSD 4GB card included Refer page 17 of user manual below for trouble shooting volume issues