This may or may not be related. I've noticed that when I change from a 7.1 processing mode to Stereo upsample I still see the icon for all 7 speakers displayed on the front pannel.
Could this additional bass in the mains be contributed by the "small" speakers' crossovers ?
( I haven't installed the update )
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HT:
990/770
Oppo BD83SE
Pioneer Elite DV-47A
Magnavox HDMR513h DVR/DVD-R
Sony DVD megachangers-2
Sony CD megachangers-2
Monster power centers-2
Sony 48" rear projection SDTV
Roku video player
JVC AL-A158 Turntable
Polk RT-2000s,CS-650,XS-650s,RT80s
LFM-1EX
Hsu VTF-1
12" Velodyne

Family room:
OPPO 970
Sony 32" direct view HDTV
Denon 3801
Rolk RMs