I purchased this super handy unit about 12 years ago. It's Canadian-made and in great physical and working condition. It's essentially a portable mini digital audio mixer for your camcorder. The DXA-4 adapter allows you to attach two balanced XLR audio devices to your camcorder. Each input signal is sent to a MIC/LINE switch to allow you to set the proper level, then to an audio control to adjust attenuation. The balanced input signal is then converted to an unbalanced output through an impedance matching transformer. Finally, the output signal is sent through an attached shielded cable terminating in a stereo mini-plug that connects to your camcorder's microphone jack. DXA-4S is designed for optimum fit on the Sony TRV900, D100, PC100, or any other Sony DV & Digital8; Canon Optura, Ultura, or Elura camera.