Not a Lampizator Amber II DAC owner, I believe the drawer below pc socket is the fuse holder, some design store a spare fuse in that drawer.
https://www.sunrom.com/img/p/682/682_800.jpg
http://newwiki.arcadecontrols.com/images/f/fc/IECFuseHolder.jpg
https://www.sunrom.com/img/p/682/682_800.jpg
http://newwiki.arcadecontrols.com/images/f/fc/IECFuseHolder.jpg