My experience is that it is highly undesirable to use AVC when recording music on my Sony minidisc. However it is then important to set the manual input gain to a fairly high level.

Sony make two mikes specifically for minidisc. One looks like a normal mike and has to stand alone. The other is very light, T-shaped and can pluc directly into the mike socket. However, if used that way it does indeed record a significant amount of intermittent motor noise. However it can be connected remotely by a standard stereo lead with the appropriate connectors with excellent results.

Richard