I have last years Onkyo model 777. If yours works basically the same,when you select the sub in on the configuration menu your other speakers will be crossed at 80 hz. (large) or
100 hz. (small). Even in the large position I
feel it takes to much away from the mains. Is your lack of bass problem in all modes? When you listen to music in stereo mode with the sub configured off,is there enough bass?
I have similar complaints here. I think that Onkyo should of put a loudness switch on these receivers for low level listening or
a way to use the sub plus mains in non cut off mode. Another item to check is the LFE
level in the menu on Dolby Digital, DTS source items. On DD the setting should be 0 db, on dts it should be +10, if your model is similar. When I purchased my Onkyo, I was
under the impression that DD receivers were
putting full frequency response to all speakers in the room and therefore would
need full range speakers around the room. It
seems that this format is set up primarilly for satellite type speakers. Does your receiver have front channel out -in jacks?
If so Onkyo says you can hook an EQ. in the loop there to improve front channel response.
Ron