I recently purchased a 6-speaker surround sound system for my
computer, Logitech's Z-640:
http://www.amazon.com/exec/obidos/tg/detail/-/B00006HYPD/qid=1078884712//ref=pd_ka_4/002-7982397-2000056?v=glance&s=videogames&n=507846

After purchasing, I needed a new sound card in order to hook it up, so
I purchased Sound Blaster's Audigy LS for $70 at Best Buy.  I
installed everything and
everything seems to be working fine.  I think I have some general
questions with my computers surround sound system.

I want to use my surround sound to the fullest extent possible.  Right
when I installed, only 3 of the speakers were exerting sound, and I
went to the "EAX Console" and enabled CMSS and now sound comes from
all speakers, as I can set the percentage of stereo focus.  I was
wondering, would most people adjust this setting?  I mean, if not, the
other speakers would just be sitting there doing nothing?

Also, I heard some people say things like when they are watching a DVD
on the computer, they can actually hear the sound going from speaker
to speaker, etc.  Would that happen automatically if I have the
speaker set just installed?  I'm just a little worried I don't have
some things set up properly.  But right now, I'm getting sound from
all speakers, so that's good, including the subwoofer of course.

I think this related to different "channels"?  I'm really just worried
I'm not getting the most I can from the speakers.  So if there's any
computr speaker junkies out there, please advise. :-)

I think I need an overview about all this junk, I'd really appreciate
if someone can come in here and give it all they got and hopefully
after they respond, I'll be much less confused on this surround sound
mess.

Thanks,
Dan

Hello.

Your problem is the fundamental problem of any home theatre surround
sound system...

Before I go any further, let me differentiate between sound from
movies and sound from music...

The first (sound from movies) is often encoded with surround sound in
mind so that each one of your speakers (4, 5, 6 or even 7) can be
assigned its own sound track to represent directional audio
faithfully.
In this case, the audio channel distribution happens automatically
(make sure you switch to DDolby Digital or Dolby Surround and turn off
all DSP effects first).

For older movies however that have been mastered in stereo or simple
audio tracks (such as MP3s or tracks from CDs - the second category -)
you're facing the problem that these audio files contain just two
tracks (left and right) and you're trying to spread them over 3 or
more channels (=speakers).

This means that you're leaving the guesswork of what is supposed to be
heard from where to your sound card and your sound card's software.
There are a number of DSP (digital sound processor) options in your
Audigy EAX menu to allow a pseudo-surround distribution of your stereo
soundtrack across all speakers.

This often takes advantage of delay and reverberation to distinguish
between sounds that come from the front and sounds that come from the
rear...

In any case though, you will never achieve the same effect as that of
a purpose-mixed dolby digital 5.1 or 6.1 soundtrack and quite often,
it is best to leave your rear speakers inactive during a movie,
especially for films that contain little sound effects and much
dialogue (everyone will otherwise sound as if they're stuck in a
well!)

Best way to understand when pseudo-surround is suitable is to
experiment a bit each time before you play a simple-stereo film.
Fine-tune the stereo focus and see if you get a desirable effect. Turn
it on and off occasionally and train your ear to understand the
differences.

In general, don't always try to use all your speakers at once just
because you paid for them...
They've got their purpose and each one is designed for different sound
frequencies (for example, the middle speaker is mostly for dialogues
so using it to play music through it distorts the whole effect).
Same thing for the sub.

Hope this helps!

Greetings, 
I am just a browser here but I thought this link would help>
http://www.logitech.com/index.cfm/support/products/document/US/EN,CRID=322,contentid=6973,contentid2=6026,showalldocuments=0
It answered most of my questions when I had a problem with my Z-680
system. It makes for a good overview anyway.

U can check out this site if u want to know more about converting yru
stereo source to a 5.1 sound system,
http://www.cineplayer.com/surroundplugin/features.asp

Check out this site for knowing the technology used
http://www.sensaurashop.com/demos

SHiNE//