According the
Super Audio CD System Description, Part 2: Audio Specification, Version 2.0 (March 2004), part 3.2.1.2.4.3: '
All Audio Channels, including LFE [channel #4 in SA-CD channel mapping]
, are always full bandwidth and have equal audio gain'.
That provision was not part of the earlier relase to this specification I know of (
Version 1.3 of June 2002).
But the
ITU-R BS.775-2 standard (July 2006), Annex 7, aknowledges that
contrary to the film industry, the music recording industry produces SA-CDs (and DVD-As, by the way) without a 10 dB gain offset.
Have there ever been multi-channel SA-CDs with LFE channels having a -10 dB gain offset, like in movie releases?