Update March 22, 2010:
After almost 3 years, the speakers still perform well. I haven't experienced any buzzing or hum that some people complained about.
This was my first review on Amazon, and I see that I wrote it mostly for the audiophile audience. So here is a quick summary:
These speakers have more liveness and less distortion than you'll likely find anywhere close to their price. They sound best with close-miked instruments and human voice. Although they have no subwoofer, they carry enough convincing bass to make all forms of instruments sound fully rendered and not tinny. Put simply, these make other computer speakers sound harsh and/or anemic by comparison.
You need to be careful with placement. Keep the speakers away from the wall and do not pack objects close to them. Use the supplied mat to couple them to a solid platform. The result is very even midrange and midbase, sweet treble, agile dynamics, and wonderful 3D imaging right at your desk. They should satisfy everyone for near-field listening who doesn't require a strong bass foundation. But make no mistake, these will out-perform some 2.1 systems just because they can really punch!
Now, for the audiophile in you, here is my original 2 part review:
I have listened to speaker systems costing less [Logitech (Z-10 + others), Creative (T-20 + others)] and more [Bose (companion series 2, 3, and 5)] than these speakers, but none of them had the dynamic snap and even midrange of the AV 40 speakers--I could tell that just listening in the store. Of all the others, the Bose companion 5 sounded the best in-store (better demo setup, too)--but it fell far short of the AV 40s. I wish I could comment on the comparative focus and realism of the speakers, but I only took the AV 40s home and not the others, so there's your caveat for the rest of this review.
The first thing that impressed me was the imaging behind my monitor--but I was also a little disappointed initially, because I was used to the in-your-face treble of cheaper speakers. Vocalists and lead instruments sounded a little recessed, but focused and not lacking in detail. Things quickly got better after the amp warmed up, and since that time, I haven't noticed a recessed sound, and the speakers seemed to open up. So I think the amp+speakers do need a little breaking-in or at least to warm up in order to sound their best.
Even when playing simple recorded voices from YouTube, I was struck with how focused and life-like the voices sounded. I could hear more parts to my CDs than before. I played "Step Into Liquid", and immediately noticed how overly processed recordings ("Back to You") sounded somewhat better, while cleaner tracks ("Endlessly", with deep harmonized vocals, percussive hollow woody instruments being thonked, etc.) totally blew me away! The voices and percussion sounded beautiful, rock-solid, and much more lively than I recalled hearing on cheaper speakers.
These speakers can deliver a very dynamic punch on the right music. I played "La Folia" on track 11 with the drums, and I can't recall ever hearing such a palpable impact on the attacks except when I played that CD in a car which had MB Quart speakers, known for their high dynamic kick. We're talking midrange kick, not bass--if you hear the Bose system, you'll understand the difference (Bose seems to put all of its dynamic response into the bass module, with mids and highs sounding lifeless). There was plenty of bass to satisfy a music lover, but probably not a bass lover. For near-field sound, it's perfect.
Because the sound was as good as it was, and because I played these using the built-in sound chips on my motherboard (Dell Precision 390), I was motivated to buy an M-Audio Audiophile 2496 sound card to see just how good my system can be on a budget (to be continued, below).
I recommend these speakers to anyone who cares about clean reproduction and approaching that sweetness and liveness that better components can offer. I paid $150 + tax.
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This is a follow-up review. I installed the M-Audio Audiophile 2496 sound card, and a 1 meter pair of Audioquest Diamondback interconnects. The sound card/cable combo required about 3 hours to break-in (initially, the new components made the sound restricted and somewhat bass-shy).
But after 3 hours, what a difference:
1) Bass was now tight and extended, and I realized I had been hearing a slight bloat before. So I flicked the bass boost switch on the speakers, which gave a small boost to the lowest range of the speaker--no coloring of the midrange per se (human voices remained unchanged), but a lift added from the upper bass on down. If the bass was not so tight and well-controlled, using this switch would have been unacceptable. In fact, before the upgrade, the switch WAS unacceptable.
2) Treble was now extended to my liking, with a remarkable smoothness (lack of grain). No peakiness, just good honest extension.
3) Better imaging, better focus (definite placement of instruments; more palpable).
4) A sort of constriction had been removed. I could enjoy a more emotional flow to the music--better dynamic response.
I could now play some of my best CDs and get that level of excitement I had felt was missing before. These included "Just Friends" by the LA4, "Modern Cool", by Patricia Barber, and "Salamander Pie", by Jay Leonhart. These CDs were missing that magic breath of life before the upgrade, but now they were "in the zone". Vocalists and instruments consistently had more presence. The timber of drums sounded much more correct. Guitar was sweet and plucked bass was outstanding (pluckier, better defined, less boomy, but nevertheless full on the bottom).
I played Vaughan Williams' "Fantasia on a Theme by Thomas Tallis" with the sound card volume maxed out and the speaker volume over halfway--really loud! I wanted to hear the massed strings get muddled, harsh, break up. The music hit its high crescendo, I waited, clenching my teeth, and--it all held. Instruments stayed well-defined, and those massed loud high notes never became grainy or harsh. They just got very, very, loud... Oh, and the bottom was definitely missing from this orchestral work, even though I was getting plenty of 'motion from the violins.
Clannad "Macalla", track 1 (low voiced choir)--mission accomplished. Fresh Aire III--mission accomplished, but... I noticed that if there was electric or synthesized bass in just the right area, I would hear a resonance in the mid-bass on a couple of notes, but I think it's more due to the speakers' location on my desktop in the corner of my office. This could be mostly remedied by knocking back down the bass boost switch.
I even went back to YouTube and listened to some of the audiophile recordings there and was impressed once more by the sound quality. Try searching for "Greek Audiophile" for an example.
A final caveat: in my room, I am using a very dead-sounding wood-and-steel-frame modular table from Ikea. And I use flat-screen monitors, with the speakers to the sides and slightly behind them, about 4 inches from the back wall--no obstructions on either side of the speakers. This means there isn't much interaction between the M-Audio speakers and my office furniture. And last but not least, I had chosen the Audioquest Diamondback cables to help balance-out this speaker's profile, in that they are very extended in the highs, and just slightly on the lean side.
In the end, I found the AV40s to perform best on human voice, percussion, and bass. They work well with chamber ensembles, close-miked instruments, and basically anything acoustic that has a nice dynamic character. Acoustic guitars hold onto their honey-sweet character. Horns and flute are without annoying peakiness or harshness. And it all comes across full-bodied in character.
So, in summary, the AV40s are capable of a high-end, uncolored, and engaging sound. And they will further reward your efforts if you hook 'em up with better interconnects and a "music-oriented" high quality sound card. For the price, they are in a league of their own.