Lol resurrected from the grave...
Clob, I picked up a pair of Sierra-1's and moved my Ascend 170SEs as rear speakers. The Sierra's are not as critically neutral as the 170SEs (about +/- 0.5db wider variance than the 170SEs). The 1" vertically laminated bamboo enclosure however is so acoustically dead (equivalent to 3" of MDF) that you (as far as I know) cannot find bookshelves at any price point that have such low cabinet resonance. This, THD, and decay times are the three major things that affect a loudspeaker's clarity...the Sierra's have the first in the bag, while the second and third are no worse than the competition at this price point (as far as internet direct speakers go).
I got a single SVS SB-12/plus subwoofer (in piano black to match the Sierra's, hehe) which are phenomenal little subs, for a 40lb sealed sub to hit 22hz +/-3db at it's price point is almost impossible for a finished sub...it's closest competitors at this price point (Epik, Elemental Designs) have either unfinished cabinets or are DIY kits. Anyway, sealed subs are GREAT for music. I got a mic and EQout out the frequency response of the sub to blend in with the speakers. I can't even tell there is a sub when I play music. They say that's a sign of a great subwoofer; you can't even tell that it's there.
Although I have to admit the new SVS MBS-01 bookshelves look PHENOMENAL at the $1k price point. The are almost 30lbs each, but are of MDF construction so from a cabinet resonance point they won't be close to the Sierra's...they are ruler flat like the Ascend 170SEs but are superior in every way...The tweeters in this speaker are $400 alone from Scanspeak (not talking about enclosure cost, cost of the wood or piano gloss finish, the midrange driver, the crossover)...The Sierra's in comparison have $130 SEAs tweeters...although to offset this the cost of cutting VLAM bamboo is prohibitive, even the highest industrial strength diamond tipped drills wear quickly with this material Either way this shows the quality of internet direct speakers and how much you get for the price you pay.
Another thing to mention is AV123 is now selling X-LS encores for $299, apparently half the cost alone are in the drivers. From what I hear they are every bit the acoustical equal of the Ascend 170SEs, although the latter may be slightly more neutral (with the encores with superior bass, which is a trademark of AV123 speakers).
Anyway below are the MBS-01s and the frequency response...
Back on topic for the Logitechs...
As far as PC/desktop speakers go, most companies are moving toward ipod-centric speaker systems and moving away from gaming speakers. Klipsch and Altec Lansing are both selling excellent 2-way speakers for the ipod. It's no surprise for music even Logitech has adopted 2-ways (Pure-fi Elite, Z-10, Z-Cinema)...when competition exists, the consumer has everything to gain, the quality goes up. Whereas Logitech has so much dominance in the gaming sector, they still have an obsolete 1-way system (Z-5500s) as their flagship due to lack of competition. It's all economics...no reason to make a better product if there is no need to.
In regards to Bose...if you like it, all the power to you. But most of the disdain for Bose is it's high cost in relation to what you get...those untreated 2" paper drivers that Bose uses in everything they make cost only a few dollars to manufacture. The enclosures are plastic, which is about as bad as you can get in terms of cabinet resonance. For me Bose is kind of like fancy restaurant food...it looks nice, and you feel "obligated" to say its nice as well...maybe it doesn't taste that bad...but you'd retch if you knew the quality (and what) they used as ingredients.