Sorry to be so late adding my comments, I don't peruse the forums like I used to. The thread I started 12/03 about this is still there but not found when searching the archives. I've owned late-model 2.3s for a couple years now, and compared them at length to 2.4s with very good equipment at a store when I posted these observations, and still stand by them:
http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1072120269&openmine&zzSdecker&4&5#Sdecker I've heard 2.4s a number of times since, but my listening impressions between 2.3 and 2.4 have remained clear to me. I'm sure by now the original poster has kept his 2.3s or moved on, but I have a couple comments. No doubt if I had 2.4s at home for awhile I'd pick up on even more subtle differences (hopefully improvements).
Swklein's initial post effectively said in a couple sentences what took me a couple paragraphs in my original post. The 2.4s clearly have more warmth and openness through the mids which does move it slightly closer to a more-relaxed Vandersteen (and others) sound while retaining the best aspects of Thiel's analytical side too. I also found the 2.4 to have a bit more bass energy, but no less lower-treble forwardness, and even more top-end sizzle. Also they're a bit easier to drive, as has been pointed out, but I'm fortunate to have a high-current amp with plenty of guts into difficult loads (ie my 2.3s), and ditto for the hardware I had at my disposal when comparing the two models. I think some of Dewinkle's observations are due to his amp and room limitations.
Cinematic_systems throws in a wrench. I have no reason to discount his frustrating experiences trying to mate these speakers to his rooms and electronics, I'm sure he spent all the time he suggests trying his best to make them work. OTOH, tons of 2.3s were sold from dealer showrooms worldwide, weren't they Thiel's most popular speaker ever, at least then? And while he gives full credit to the 2.4, I just have never heard such a remarkable difference between the two such that the "2.3 is a bad speaker with many problems and the 2.4 corrects them all".
I've measured my 2.3s in my room (admittedly near-ideal setup and acoustics) several ways in lots of positions and don't find a boosted top-end or big crossover suckouts, but it does show a certain upper mids forwardness, just as I also heard on the 2.4s, and what gives all Thiels their 'bright' reputation. Good electronics are essential, though I haven't played with speaker cables or interconnects (yet?) to try and alter the sound. My 2.3s are many feet away from any walls, 8' apart and 9' from my ideal listening position: those with narrower, brighter rooms may have more setup problems than I've encountered, but my guess this would apply equally to 2.4 as it's at least as 'bright' to my ears. Both speakers have very little radiating area for their price/size, a 6.5" (cone-diameter) woofer and 2.5" mid, combined with the shallow crossover slopes and huge number of crossover components I feel limit their ultimate SPLs and microdynamic transparency more than say a B&W 804 with larger cones and steeper slopes. But what sonic tradeoffs for time/phase alignment?
I've read all the reviews of both speakers and we all know you gotta try and read between the lines. My take is the 2.4 is better received by the press as a whole than the 2.3, despite its having purely evolutionary tweaks on the same design. But as cinematic_systems points out, in 5yrs technology marches on and lotsa small judicious improvements can change a speaker's character substantially for the better.
Which comes down to the same thing Buda offers. Is the 2.4 worth upgrading over the 2.3? Yes, I feel it's definitely a better speaker that offers more bass, fills in the lower mids, has a more transparent midrange presentation, but doesn't alter the accept-it-or-hate-it upper mids forwardness, and is at least as hot on top as the 2.3. The 2.4 does some significant things a bit better than the 2.3, the 2.3 probably does nothing better than the 2.4, but I think they equally share many of the same attributes and deficits. But let's face it, the speakers sound very similar to each other versus either Thiel to any other brand of speaker.
I haven't figured out how much *I'd* be willing to pay for the upgrade on the used market as I'm off the big-ticket merry-go-round for awhile. If the 2.4s were traded straight up for my 2.3s I'd sure do it, but knowing that there's always better audio components out there, and I remain satisfied with my 2.3's presentation, I'll leave well enough alone for now.
Sorry, I guess I'm getting sucked back into the hifi fray again :-O
