When you are using analog pre-ins from say a Bluray player with preouts, the Bluray player has no bass management abilities, so what the Denon does is let you select between +15db, +10db or +5db increase in bass. In most cases because of lack of bass management using analog connections, the bass is severely lacking, so Denon just does it for you, when you find a setting that matches as close as you would like. It is only to be used with the analog inputs, say from a SACD, DVD-A or Bluray player without the need for HDMI (Although I figure anyone with a 3808 would use a HDMI).
