5ch/7ch stereo in 5 channel mode

SW means sub woofer, not necessary means center speaker in all receivers. Instead of setting 5ch stereo, if you have 3 speakers. try to set "3channel" or "simulated". If you own more than 3 speakers, you may refer to the user´s manual to correctly wire them to get the full sound.

Do you listen to audio CDs via a CD player or DVD player? Pure audio CD is only 2-channel, so either TV or the DVD player is doing the mix to 5 channels. But you can choose the sound mode via remote - there should be modes like 5ch/7ch stereo, where the same signal is going to all speakers (I you this mode for listening to radio sometimes).

maybe you need to replace a fuse?
is it hooked up correctly

THE BEST SOUND IS WHAT SOUNDS BEST TO YOU, HOWEVER DO THIS:
1, USING THE SETUP MIC CONFIGURE YOUR DENON, PAGE 8 OF THE MANUAL. NEXT
2. RAISE THE REAR SPKR LEVELS, PAGE 46,47. NEXT
3. WHEN LISTENING TO AUDIO CD OR RADIO TRY THE 5 CH STEREO DSP MODE.
4. WHEN WATCHING A DVD USE DSP DOLBY PROLOGIC OR TRY 5CH STEREO IF THE MOVIE IS MOSTLY TALKING.
5, TRY 5CH STEREO WHEN WATCHING PROGRAMS WITH MOSTLY TALKING

On this reciever you have rear surround and rear back spkrs, if your using the surr back they have to be assigned if unassigned in the settings. If using rear surr spkrs change your surr field to 5ch stereo and your rear speakers will work.
There is no 7.5 unless you have 5 subs the 7 is the total number of speakers and the .1 is the number of subs in the system

Make sure you have an anteena connected and adjusted

set it on dolby digital mode not sterio mode should be differnt modes on a ch only use prologiic or spin the mode dial to doby digital on movie on direct tv wont be dobly fake suround more less but center should work change settings modes

Make sure the input setting is set to 'Auto' while on those channels and not Analog.

When using analog cables, switch the setting on the amp to 5CH STEREO or 7CH depending on your speaker configuration. This will give you consistant audio. Another option is to use either optical or SPDIF for digital sound. Good Luck.

If the surround back is turned on,on the receiver,then the 7CH stereo will activate the 2 rear,but if it's off on the receiver the 5CH on the remote will do the same. I don't know much about the unit changing from 7CH to game,rock Arena etc.that i know will happen if u press the DSP simulation found @ the 3rd. top right button on the remote.