THX certification is all relative and is based on many things, generally not what they sound like though. It's more a measure of noise level, frequency response (this is a statistic given by the manufacturer), and a few other things. It's a great marketing tool but as far as actual real-world testing, the standards by which multimedia speakers are judged is NOT the same as home theatre, movie theatre, or any other THX specification. Multimedia speakers have their own specification. Since Klipsch are definitely one of the best sounding speakers among multimedia speakers, of course they have this certification, there isn't a whole lot to compare it up against, and who's to say Boston, or any other company has TRIED to get the certification? It isn't just awarded, you have to ask for it. Here is some more information on THX multimedia certification:
http://www.thx.com/consumer_products/mm.html
As you can see, Alter Lansing now also has a THX certified speaker set with the ADA885's.
My first real question though is that, if you haven't heard either one of these systems, how are you arguing this point with me? heh.. I mean, sure the Klipsch have a couple advantages over the ACS54's. Let me tell you what they are. Number one, they're louder. Number two, they handle more power. Number three, they have a LOT more bass.
My statements were merely a recommendation on which is a more rounded system. When you listen to music, the thing that makes music sound "warm" is the midbass and a speaker's ability to reproduce it. Highs and lows are important, but to balance it out and round out the sound, midbass is extremely important. The Klipsch ProMedia's have horn tweeters and a huge woofer (8" is very large by Multimedia standards) to reproduce the sounds. The 3 1/2" woofer that they have just isn't enough to overpower the powerful tractile horn-loaded driver. Generally an 8" woofer could reproduce decent midbass, however, in this case it is used as a subwoofer and is built in a ported cabinet appropriately, and is only tuned for low bass. Horn tweeters are great for anything above 5khz. The problem lies in your frequencies above 150hz (properly tuned subwoofers will even be tuned to cut off much lower than this approximately 80hz) but for argument's sake, let's say the Klipsch is tuned from 25 or 30 cycles (25-30hz) up to 150hz. This is probably the largest frequency range this speaker could handle. The problem is, where are your frequencies from 150-5000 hz being produced at? That 3 1/2" speaker. The horn tweeter is simply too overpowering for my tastes, some would disagree. Typical multimedia speaker configurations have a tweeter as opposed to a horn, a mid-range driver (3 1/2 to 5 1/4 inches) and a subwoofer (5 1/4 to 8". The Klipsch is unfortunately lacking a nice "warm" sound, at least from what I am used to. Again, some would disagree.
The reason I prefer digital output, versus analog, is the fact that I've tried both. I personally don't use multimedia speakers and output my sound to my home theatre. My choices are either 1/8 -> RCA plug or an optical connection which is directly on my soundcard. The optical plug produces a more natural flat response, and 1/8" connectors just aren't good for high-fidelity sound. They are adequate for most multimedia setups but not for a true hi-fi connection.
I've tested the promedia's on a couple of different sound cards, not only the Live! series, however, I have not had a chance to use the Philips card. If I can get Boston Acoustics speakers to sound awesome on another card that the ProMedia's do NOT sound good on, that tells me if the PM's sound good on the Philips card, the Bostons will only sound that much better. I still can't see how the PM's will sound good, merely by changing the sound card, this is a speaker driver issue, not a soundcard issue.
divinemartyr