Specs below: Uses an AD823 op-amp. Runs on 2 - 9 volt batteries. Case is 1"x1"x5" black plastic case. Has one set of analog outputs(RCA). Has a stepped volume control. Has a 1/4" headphone adapter. Can drive any headphone to very loud volume. If interested you can email me for pics. Asking $95 shipped in US. MO only.