Superb!

This is an updated review on the Logitech Z-2300 after a heavy break-in and some additional information.

If you don't want to read the whole review. I can sum it up right here. It sounded fantastic for a computer speaker system. BUY IT.
When I first bought this speaker. I was a bit skeptical. I thought, huh, a single 2.5 inch driver trying to produce excellent sound? BUT, when I hooked them up and tested them out, WOW!!!! There is some serious sound coming out of these speakers, read on.

Design

The Logitech Z-2300 utilizes a single 2.5 inch phase plug driver in each of the satellite speakers. The subwoofer sports an 8 inch driver. The satellites use 40 watts each and the subwoofer uses 120 watts, making a total power output of 200 watts. This is a BIG sub for a computer speaker. This system is also THX ceritified. Note that this is just a near field THX certification. Real THX certified speakers costs a lot more. Logitech included a stylish wired remote. It has a big volume dial, bass volume dial, a power on/off button, and a headphone jack.

For people who don't know what is a phase plug is, it's a driver that uses a central "bullet" instead of a dust cap. The purpose of a phase plug is to reproduce the higher frequencies of sound better for a driver. It improves power handling as well. Although I'm surprised that Logitech did not include a separate tweeter in the speaker since a phase plug's job is not to reproduce the treble, nor to replace or "outperform" as Logitech says it a two say setup. It's job is to help reproduce the high mids. The satellites are connected to the sub via a 1 meter RCA connection and the wires are permanently attached to the speaker. The length might not be long enough for some people, but it should be fine if you just plan to put the speakers on the desk.

Bass

With an 8 inch driver and 120 watts, it's going to produce some serious bass. What I found is that the bass is this system's biggest weakness to an audiophile. I find the bass from the subwoofer pretty boomy, not tight enough, and it's slow. Some people might like the boominess, but as an audiophile, I like tight, smooth bass. The sub definitely pounded. It didn't distort until I reach 75% of the volume (that's LOUD!!!) But it didn't shake my 4.5m by 3m room. It only vibrated my floors. That's because the sub wasn't able to reach down low. The sub had some usable bass output at 35Hz, but not much output lower.

Despite all that criticism, it is still the best and loudest bass I've heard coming out of a 2.1 computer speaker. The criticisms are picked out by the pickiest audiophile like me.

Midrange

The midrange was fantastic for a 2.5 inch driver. It was very smooth and warm. It was very natural and therefore it sounded very good and clear.

Treble

The speakers did an excellent job reproducing treble. The treble is not shrill, but the upper treble was a little bit bright. The low to mid treble was reproduced with so much clarity that rivals many floorstanding speakers! The treble sounded excellent when you play any music on it.

Imaging

The imaging is very good for such a small speaker. Watching a movie such as The Matrix Reloaded, the part where Trinity tries to kill an agent using two 9mm guns. That part had a lot of the whooshing sound effect. When I was watching this part, the speakers produced a very realistic sound recreating the scene. In fact, the imaging is so good that it's almost like having an invisible center channel speaker.

Overall

This speaker sounds so good that I forgot that they're only $100. Then I realize each speaker in my living room cost more than 10 times the price of this system. I didn't find myself to "miss" my reference system in my living room. This system's ability to reproduce sound so accurately is shocking. These speaker will reveal the weakness of mp3 compression (192K or less)! I didn't find music to be their biggest weakness like many systems. But I do find watching movies is more enjoyable than listening to music since movie somehow "conceals" the weakness of bad speakers. That's why it's easier to judge sound quality using music rather than a movie.

Is it a good buy?

Oh absolutely. It will kick all of the competition's a**. Although I recommend to get these speakers when they are on sale since $230 is a lot to pay for a computer speaker. I live in Canada and I was able to get one for $100 at Best Buy.

The inevitable comparison

There are currently 5 high end 2.1 systems in the market. They are the:
Logitech Z-2300
Klipsch Promedia 2.1
Harmon Kardon Soundstick II
Altec Lansing MX5021
Altec Lansing FX6021

The Logitech Z-2300 is the winner in this group. (after break-in)

Logitech Z-2300 vs Klipsch Promedia 2.1

The Klipsch's Promedia sounded excellent. It sounded almost identical to the Logitech. Even though they had a tweeter, they didn't produce better treble than the Z-2300. The Klipsch also had a less powerful sub, and the satellite speakers are huge. (1.5 times bigger than the Logitech's satellites) Worst of all, the Klipsch's build quality was horrible. The amp was a BIG problem. You can consider yourself lucky if your's is still working after a year. It was also slightly more expensive than the Logitech. Logitech is the obvious winner.

Logitech Z-2300 vs Harmon Kardon Soundstick II

The Harmon Kardon's satellite as good as the Z-2300's sattelite. But, the speakers produces a bit of sibilance. (which may result from people thinking that they sound better) Although they sounded excellent, their sub is atrocious. The sub sound very good, but it was too weak. Forget about shaking the room, it won't even vibrate your desk! Logitech wins. The Harmon Kardon had a very weak sub, not THX certified, and it was more expensive than the Logitech.

Logitech Z-2300 vs Altec Lansing MX5021

The Altec Lansing sounded excellent, beating the Z-2300 in the low mids by a little bit.(two 3 inch drivers vs one 2.5 inch) Otherwise the Z-2300 sounded better. Altec Lansing has a stupid tradition, and that is their speakers suffer from weak bass. Also, the price is higher than the Logitech. The sattelites is much bigger than any computer speaker I've seen. Logitech still wins because they are smaller, much better bass, cheaper, and the Altec sounded overall inferior to Logitech.

Logitech Z-2300 vs Altec Lansing FX6021

The Altec Lansing's satellites had the overall worst sound. Weak bass. weak low mid, only acceptable midrange, and weak highs.(18000Hz at -10dB!!)The midrange wasn't good. The Altec Lansings also suffered from weak bass. This system isn't THX certified. This system is also VERY expensive. Almost double the price of the Logitech. Logitech wins.

Conclusion

I hope this review was informative and helpful to you. The Logitech Z-2300 are superb speakers. Just buy them, and you will not regret your purchase.

Appendix

I'm sure people have read reviews saying that the Logitech Z-2300 lacks midrange, bad sound, etc. Now I have an explanation for these reviews. It seems that the bad sounding Z-2300s are founded pretty often (I'm lucky that I got a "good" sounding set). The bad sounding ones sounds pretty bad. I suspect this problem is because of the amp in the sub because I hooked up the satellite speakers from the bad sounding set to my goos sounding set, the sound is equally as good. When I hooked up my good sounding satellite speakers to the bad set, it sounded horrible, just like the original bad sounding satellite speakers. I've also checked if the problem is a bad cable or a bad soundtouch remote, it's not. I pluged my headphone into the SoundTouch remote, and it sounded the same if I plugged it into my soundcard. Let me tell you how to distinguish a bad sounding set of Z-2300. The bad sounding set will sound like your headphone that came with your iPod or any other headphone that came with your MP3 player, except with a lot more bass. (except Sony noise cancelling MP3 players, the headphones that came with Sony MP3 player sounds much much better than the normal headphones that come with your MP3 player. (but not as good as a good sounding set of Z-2300) ) The good sounding set of Z-2300 will sound MUCH MUCH better than your headphone that comes with your MP3 player and also everything I've said in the review. If you get a bad set, I recommend you to get an exchange with the store if you can. Otherwise, you have to call Logitech about the problem. They will give you another set, but you have to send the bad one to Logitech. Good luck.

Customer service

I contacted Logitech's customer service to see how good is it. I pretended that my speaker broke. I told them that the system just stopped working. Then they told me to check the connections if any of the plugs are unplugged. After that, they just asked if I voided the warranty by opening the sub and asked for a PID number under the satellite speaker and a serial number on the sub. Then they told me that Logitech will be sending me a brand new set, and I don't even have to send the old one back! Of course after I told them to stop and it was for a review to judge the customer service. That is the BEST customer service I've ever received. Not only their product is great, but Logitech stands by your product. Excellent job Logitech!

I asked Logitech about how a phase plug driver outperforms a two-way design. Logitech gave me a convincing and reasonable answer for that statement. The answer has been "translated" for better clarity.

Logitech chose to use a phase plug driver instead of a two-way design because it outperforms a two-way design in a following ways.
A two-way design has more components needed than a full range driver. A two-way speaker need a tweeter, and a crossover. More components equals more cost. Because of that, we either have to cheapen the components, or to raise prices. If we have two-way speakers in the Z-2300 and still keep the price at $150, we have to cheapen components. Cheap components = inferior sound. By using a full range, phase plug driver, we elimanate the cost of a tweeter and crossover. The money saved from the extra components can be used for a very high quality full range driver and therefore producing a better sound than a two-way speaker for the same money.