Logitech Z680's Digital/Analog

The "digital" or "analog" cables are determined by the requirements of your speakers and the availability of digital and/or analog output from your sound card.  If you have "analog" speakers then you need to use "analog" cables.  If you have "digital" speakers and a digital output on the sound card then you need to use the type of cable specified for the system. 

Normally, the cables supplied with analog speaker systems are more than adequate for those systems.  Using "designer" cable such as "monster cable" won't really add or improve anything. Using "hard wire" digital cable (not fiber optic digital cable) for analog could even degrade the signal because of the electrical characteristics (properties) of the cable.

Hey Jett,

I have the same speakers. Pretty awesome, huh? The digital cables they're referring to are for seperate components to install into the back of the controller. Like if you wanted to add a DVD player witha fibre optic digital cable, or a DVD player with a coaxial digital cable. The speakers just plugged into your PC from the subwoofer is just Analog. Did this help?

Bob

Jet,

Wow! You know, I forgot all about that option. I'm sure the sound must be better. The manual states that the digital is not available for DVD playback, but that doesn't really bother me. I have a Audigy 2ZS for my Sound Card too. That has kind of a funny digital output. It's just like a regular jack. I have to find some type of adapter that can hook into the Optical jack on the controller. I'd much rather use the Optical than to Coaxial. The manual states something about a four pole jack for the card. Any ideas where to get the adapter? I'm going to try. I'm sure it makes a difference. It sure did when I changed my Surround Sound to all Digital. The sound was a lot cleaner.

Bob 

The difference between Digital and Analog is how the signal is processed.  For instance, speakers like the Z-680 has a digital decoder for Dolby surround, like THX.  You will notice the difference when you use Dolby Surround on DVD movies like Star Wars Movies and such and having your Z-680s set on Digital Coax (If you are using the standard Audigy 2 based card without breakout box) or Digital Optical (Audigy with Breakout box)

The difference in the cable is that Analog does basic 6 channel mixing, not using the full effect of the speakers when doing dolby surround, that is based more on what the Software interprets and sends it to the 6 different channels which will give you an Interpreted effect instead of the actual Dolby Surround the Movie is suppose to have.  Digital signals are basically a single, data signal sent at a slightly higher speed, which also means instead of sending the wave format over the wire, you are sending a pure signal of data that the Digital Speakers translates.  This means the wire will not have 'line' noise such as 'buzz' or 'pops' which is often the symptom of Analogy connections due to grounding.  If you are a pure Audiophile, this makes a dramatic difference in how you 'hear' things, or so I am told by musicians and people in the music industry (I could never tell the difference myself).  It also explains WHY Pro-Audio Speakers are MORE expensive than just the $15 speakers you can get.  Audiophiles can REALLY tell the difference between good and bad speakers versus people who don't really care that much.

Now cable wise...  You do not need a 'specific' one... You can go with a basic RCA Cable with a Radio Shack RCA to 1/8" Mono Jack converter...  Although for better quality of the signal, especially over distance, you would want gold-plated and digital rated cable, to ensure good signal strength.  Optical, you have to get the 1/8" Optical cable, no way around it and currently, there is no known way to convert the 1/8" 'stereo' digital Jack that is at the back of standard Audigy 2 cards to Optical, so you can only do this with Audigy cards that have breakout or Optical ports.

The Analog Audio only uses standard 1/8" stereo jacks, which comes with the speakers.

For most things, you will use Analog Audio, as most music does not use Dolby Surround, especially MP3s, WMAs and such.  Most games also do not use Dolby Surround.

The Audigy card that comes with the majority of the Dell Systems also uses Software based AC3/Dolby Digital Decoding, instead of the built in AC3/Dolby Digital decoding...  Hence you will not find the 'option' of disabling AC3 decoding for your sound card.  The DVD player MUST be set to 'Spdif' for Audio for your Z-680 Speakers to detect the Dolby Signal to Properly Process it.  You will also need to make sure your Z-680 speakers are SET to Coax or Optical for it to detect the proper signal...  You should see it change from 'Stereo' or 'Stereo x2' to '[)(] Digital' when it is processing properly.  Also if you have it set at '[)(] PL2 Movie' or '[)(] PL2 Music'...  It should change to '[)(] Digital' for the most part...  If it does not...  You may not have the cable set properly or you will need to be sure to turn on 'Digital Output Only' on.

For the most part, you will want Direct, 6 Channel Output...  Digital for things like Movies or if you have Music that takes advantage of Digitial Output like DTS.