Jtdylktuy

In my case, I was having the same problem, my music and most videos were on 2.1 and I only heard 2 of the 5 speakers. Videogames and some videos had 5.1 so no problem.

If you're running Win7 and you have no other than the default sound driver, there is an option "Speaker Fill" that solves all problems!

First, right click on the sound icon in the task bar (right lower corner), choose "Playback Devices".

If you have only one sound output, it'll be the only one on the list. If you have more than one then, while playing some music, you'll notice one of the device's volume bar moving, that's the one you should select.

Select your audio input and click on "Properties". Then go to "Enhacements" tab. There should be a checkbox with the "Speaker Fill" in the middle. Select it and press apply.

Worked for me perfectly, 5.1 sound on 2.1 music =D

Usually with a 5.1 speaker system on the Realtek HD,

you should get an upmix of your stereo and 2.1 audio.

Check this AVSForum discussion on Disable stereo upmix on Realtek HD Audio?

The Reaktek control app has options to select the Audio I/O for various number of channels. Maybe you need to change this to 5.1?

If you are using Windows Vista, i came across this weird discussion on
Vista and Realtek HD audio cannot provide surround sound

It's completely non-software, but what about getting an audio source switch from a place like Radio Shack and have the front and rear speakers go through it between the computer and you, so that when you're doing a non-5.1 sound activity, you can manually just switch the speakers to put the "front" near you?

If you use the realtek, download the realtek Driver
http://www.realtek.com.tw/downloads/downloadsCheck.aspx?Langid=1&PNid=14&PFid=24&Level=4&Conn=3&DownTypeID=3&GetDown=false

From the Audio Manager/Control
Select the speaker tab. On the right hand side, there are six icons of connector
Right click on pink connect icon. Select connection configuration. Select Rear Speaker
Right click on black connect icon. Select connection configuration. Select Front Speaker
Front Rear Sound will be switched

If you use ffdshow audio decoder for another programs, I found the easy way to expand.
Just use custom matrix and choose 3/0/2 - 5channel -> custom matrix and write 1 to all rows and columns 1 only BackL BackR's. I use this watching tv on my dvb card software. Really works!

Intro:
I spent several hours over the last couple days trying to figure out why there is no sound coming from the REAR speakers when playing 2.1 sources and such (streaming videos or music from online). 5.1 sound works in video games and DVD/Bluray, etc. There was no SPEAKER FILL option in the most recent REALTEK drivers.

Quick rundown of my problem:
5.1 audio only worked for 5.1 output sources, not for everything.

Interesting details:
CONTROL PANEL > HARDWARE AND SOUND > SOUND, click Speakers (typical output source.... where the sound comes from), then the Configure button.. By default, it's set to Stereo (I just built a new computer, so this is where I was sitting). Set it to 5.1 Surround and it WORKS.... for only one source (I would steam a channel on DI.fm and if I reopened that stream, it would revert back). If I reopen anything or change a sound setting, it'll completely stop or it'll revert back to stereo sound. VERY clear difference, as with stereo, the volume out the front and center speakers is way louder than on 5.1, even on the same volume setting (I was using 50%).

I would change it from 5.1, open a source, change it to Stereo, open a source. There was a clear difference, and as said before though, it only works for ONE source. Keep in mind, Windows has an audio driver that has the SPEAKER FILL option, but as you're all probably aware, it's garbage. VERY quiet!

SOLUTION:
CONTROL PANEL > HARDWARE AND SOUND > SOUND, click Speakers, then the Properties button, click the Enhancements tab (by default, Immediate mode is selected.... I left it checked, default position). Scroll down to the bottom of the list and check DTS Connect. Apply.

You can even use the Room Correction enhancement to further produce a more desired volume from your speakers based on your configuration!

Fixed the issue. I can now restart my computer, play multiple sources, etc, without having to change anything in the sound options ever again!

MOTHERBOARD: Asus Maximus VI Hero w/onboard Realtek HD audio.

I had a different problem where speaker fill WAS working for all windows sources like iTunes, Media Player, Winamp, etc however Pandora via Chrome was not filling for some reason.

I found this solution: https://plus.google.com/+UweTrottmann/posts/NkJtxz7iHMP

1. Go to chrome://plugins/
   


2. Expand the "Details" [+] button


3. Disable the flash plugin that is NOT installed in your windows directory


4. Restart chrome and enjoy speaker fill from Pandora

The freeware audio player foobar2000 has an add-in that allows you to upmix to up to 18 channels called MatrixMixer.

MatrixMixer also has a more general package, but it appears to not have been updated in quite some time, so your mileage may vary.

If you are using a Creative sound card you can turn on the CMSS Technology.
http://www.creative.com/soundblaster/technology/cmss-3d/

It claims to upmix stereo into 5.1 sound, and can be enabled in their creative audio control panel. Once I enabled it, I got output from all speakers for all my MP3s.

It disables itself automatically, if the input itself is 5.1.

If you have a creative audigy soundcard, in CMSS 3D/ CMSS Modes on audio console application see if you have "Stereo Surround" option available http://i.imgur.com/RoTTA6n.png(i have it on audigy support pack 4.0 drivers from daniel_K), this is better than those CMSS modes, in the way that it actually duplicates the channels on the rear speakers, instead of doing some funky stuff that the CMSS modes do, which i find doesn't sound too good, sound get distorted and is like, .. metallic.

The good thing of this it applies to all programs on windows. And real 5.1 sources aren't affected. The realtek "speaker fill" option i have found (at least on my motherboard) it doesn't sound too good, like the cmss modes, so i would prefer to do it manually on each application(or try other solutions like enhancements tab mentioned on other posts):

If you use media player classic (MPC is also included on CCCP and other codec packs) you can also edit the matrix in options, it's easy http://i.imgur.com/VuaoCG6.png , and doesn't affect 5 channel sources.

On foobar, on preferences/playback/dspmanager there is a "convert stereo to 4 channels", just activate it and it just works (i don't think it uses center speakertough , you may need to download a matrix dsp if you need that one).

There are lots of various ways. I've tried too many to remember and found most of them lacking greatly in the accurate reproduction department. If you're looking for "more noise" almost any of the above will work fine. I you're looking for more of an audiophile solution to using those speakers, it can be done but isn't exactly for the faint of heart.

To scare you off right up front, take a look at the screenshots below. Those are my mixer and patchbay setups. Yes, the mixer is playing two channel stereo at the moment, although it is impossible to tell. Anyway, start with 3rd order Ambisonics (jackd, ambdec, and a mitt full of plugins). Setup for a 7.1 system, even if you only have 5.1. You can try to figure it out from the pictures, but it's just all too much to describe here.

What's all this get you? Well, stereo. That's the point. You end up with decoupled speakers, and a wider, deeper, and far better integrated image with a much bigger "sweet spot". I find it much less tiring.

Non-Mixer strips and
Patchage patchbay.

IF you want total control over Windows Audio Mixer I recommend to use free open-source Equalizer APO (with Peace GUI). With this app you will be able to equalize audio and upscale stereo to 5.1, 7.1 and what ever you want. You can just copy one channel to another with scripting (yup! this soft can script audio channels! BRILLIANT!) Link: https://sourceforge.net/projects/equalizerapo/

I need to recommend Voicemeeter. Visit this site and use it to clone front speakers to side/rear speakers. It works as virtual audio device, so it works for every audio players.

THE cheapest solution (albeit most probably not the best one):

http://www.dealextreme.com/details.dx/sku.741~r.54077798