THX is a digital standard
Also important to consider is that THX certified may not
mean much other than "submitted" speakers, others may
certainly have as good a quality.
- you cannot implement digital audio with on-board
sound - you need a capable soundcard
Huh? Sound cards are generally needed for better analog,
not digital, or more I/O options.
- unless you buy an Audigy 2 ZS
Platinum or higher, you can only purchase the Creative speakers, as the
connectors on the lesser models (and I'm still talking ZS here, but the
vanilla Audigy 2 ZS) will only function in digital mode if used with
Creative speakers. If you want to buy the Logitech you would need to go for
a more expensive soundcard. IMNSHO, you should channel the money into a
decent soundcard and then save up for the speakers (and why only 2.1?)
I'm not so sure OP is trying to use THX sound, rather
wondering about the speakers as THX certification applies to
their quality. One doesn't usually get these speakers for a
home theater.
Audigy 2 ZS isn't at all good for digital output from what I
gather. It seems Creative may've been a bit dishonest in
their specs, that they're claiming high bitrate and
resolution when the weakest link, the DSP, can only do 16
bit, 48Khz. Some have even called it fraud. Maybe I'm
wrong- I dont' have an Audigy 2 ZS.
If OP wants best 2.1 sound, he might consider an Envy24 HT-S
based Chaintech AV-710, which is a steal @ $26. It has
bit-perfect digital out and pretty good 2.1 analog too.
This is assuming the goal is only 2.1 sound.
Expensive speakers are wasted on onboard sound chips (and that's what it is,
a chip - not a card). So, to answer your question, not a smart use of money
at all. A complete waste if you ask me.
Well I'd rather have good speakers than a good soundcard if
forced to choose as the speakers make a far larger
difference, but it's true that both are needed.
Particularly the analog-digital converter for analog-out
must be good, and the Audigy's ADC is good, but IMO, not
good enough to justify it's pricetag. It's value comes from
gaming support instead... not that the other alternatives
won't game, just a few FPS loss when using > 2 channels.