Year 2004 Logitech launched what was to become arguably the most successful 5.1 computer/home theater audio-system. At that time, Z-5500 was product ahead of its competition offering good sound quality, a slick design, plenty of power as well as versatility, crushing virtually all competitors on the PC consumer market. The system was, naturally, not flawless, weak spots existed, but the target customers received it with great appreciation, this being the reason for its huge commercial success. After seven years, during which it didn’t receive any major overhauls, Logitech announced a successor for Z-5500, namely Z906. In this article we tried to achieve a direct comparison between the two aforementioned products, we analyzed the pros and cons of the new model, and last but not least we tested its audio performance.

Presentation:
The first thing to meet the eye the moment we opened the box was the subwoofer. It was significantly smaller than that of the previous model, being lighter as well. After opening up both packages we started a direct evaluation of the two models:
a. Satellites
Constructively, both model’s satellites are similar, both having used same 3’’ loudspeakers belonging to the “Full Range Paper Cone” series manufactured by Tangband. The speaker membrane is made of cellulose, the suspension of rubber, whereas the shape and volume of the housing is similar.

The audio output dissimilarities arise from the fact that Z906’s satellites are of the sealed type, whereas the ones from Z5500 are bass-reflex. The satellites have no tweeters, thus their only speaker unit must cover the whole frequency spectrum. We could not understand why such a solution was preferred, as it is clearly inferior to a classical, two-way solution with regard to the accuracy of the frequency response. Exterior-wise they they look different to a somewhat larger extent: the Z906 satellites lack the outer detachable mesh in favor of a fixed metallic one. They are also fitted with silicone rubber bumper feet instead of the rotating stand we have gotten used to in the previous model. The color of the plastic case is dark gray, which is more discreet than the shiny silvery tint used on the previous model. Both models have similar aesthetics as far as we are concerned, both plastic having a satisfying build quality. Z906’s satellites have a wall hanging system in case this is required; the cable-clutching system is firm. While we are not fond of this particular solution, we believe that it is acceptable for the system form factor.

b. Subwoofer
The differences between the two subwoofers are important, both construction- as well as functionality-wise. Both encasings contain the subwoofer own amplifier unit as well as the satellites’. In the case of Z906, however, inside the subwoofer casing lies the digital decoding module, unlike the Z-5500 model, where the DAC unit lied inside the exterior console. One other easy to notice aspect is the “evaporation” of the huge metallic heatsink that stood on the back cover. It is the aluminum-made back cover that overtook the heat dissipation task; we’ve tested the system up to high volumes and it never heated up to worrisome temperatures. On the back-cover of the subwoofer lie the system analog and digital connectors. Z906 features a generous amount of connectors, i.e. multichannel analogic input, stereo analogic input and three digital inputs(two tosslinks and a coaxial input).

We’ve opened up both subwoofers in order to study their design and components thoroughly. As one can notice from the pictures, the Z906 drags its juice from a SMPS (Switch-mode power supply) while the filtering capacitors are being rather small for the declared power output. We also believe that the finals (class D) on the integrated circuits are not the most fortunate solution. The Z5500, on the other hand, has a more solid amplification unit, with a larger toroidal transformer which is seated in the opposite corner with regard to the electrical parts, the filtration is more to our liking (2 pc. 10,000uF), the finals are of better quality and the massive heatsink insures an effective cooling.

The Z5500 subwoofer loudspeaker measures 10’’ diameter and is manufactured by Tangband, the model being WT644F. The Z906 subwoofer diameter is 8’’, significantly smaller than the previous model. Unfortunately, we could not identify its manufacturer and model, but it is likely to be aTangband W8-670Q. We apologize if we are wrong; the loudspeaker has no specifications printed on, being completely rebranded by Logitech, while the producer offers no official data regarding their product’s components origin.

c. Central console, remote control, accessories
The Z906 central console has been simplified. On it, we could find the general volume knob, the individual satellites and subwoofer volume knobs, as well as the system configuration control (2.1, 4.1, 5.1, etc.). There is no longer an LCD, but only orange LEDs which indicate the status of the device, a much less elegant solution in our opinion. The horizontal layout of the console, the dark gray color of the system as well as the subwoofer’s smaller form-factor, all make this system easier to fit in a living-room, a feat we most definitely like. The remote control is simple yet very effective. The small dimensions and the ease of use make it pleasant and friendly to use. In this regard, we have only praise words: we could not understand why high-end receiver manufacturers do not include an EZmode remote control for basic menu access. We are increasingly being numbed by the lush and complicated high end remote controls, inappropriate for daily use.
The package also contains cables for the five satellites which are of questionable quality, being both thin and fragile. However we are glad to see that the user can change and thus choose cables according to his liking regarding quality, size and color, a feat we considered a strong point of the previous model that stills lies with the new one.

d. Digital to Analog conversion
The Digital to Analog conversion unit is completely overhauled. While Z5500 is equipped with Cirrus Logic (CS42526-CQZ DAC) chips, Z906 has AKM and D2Audio counterparts (AKM5386vt and D2-71583-L3). The aforementioned manufacturers are well-established, both AKM and Cirrus Logic being a good choice for quality.

TESTING:
We tested Z906 in parallel with Z5500, using both the analogic inputs as well as the digital ones. For the analogic input we used an ASUS Xonar D2 soundcard. As for the digital input we used the digital-coaxial output found on Xonar D2and the AD LABS MARS USB-to-coaxial interface.
Movies we watched:
• Burlesque (.mkv)
• Despicable Me (.mkv)
• Inception (.mkv)
Music we have listened to:
• Pink Martini – Sympathique (1999)
• CesariaEvora– Miss Perfumado [1992]
• Rihanna-Music.Of.The.Sun.2005
• Celine Dion-Best Ballads
• Francis Goya – Greatest Hits 2CD – 2009
• Dire Straits 1985-Brothers in Arms
• Chesky Records-Ultimate Demonstration Disc
 B&W-Demo
For gaming we used the exceptional Starcraft 2 as well as Crysis
At the end of the testing we performed a novel experiment. We linked together both system satellites to the Onkyo 807 “beast” in order to evaluate if and to what extent the audio-experience gets any better.

THE SOUND:
Z5500:
The Z5500 massive subwoofer shoots an impressive bass for a system of its price-tag. The solid amplification offers enough juice to the 10’’ speaker for the rendering of low frequencies. The bass we witnessed was ample and deep, lacking either outstanding precision or refinement, but being more than satisfying considering the target segment.
The middle frequencies sound cold, a feeling we’ve encountered the moment we listened to a few female voices. This downside penalizes the “live” sensation. The emotion an artist wishes to express is being lost.
The high frequencies are one of the system’s weak points. The lack of tweeters cannot be compensated by the full-range speakers, regardless of their build quality. The lack of resolution and details along the high-frequency spectrum is annoying and the listener misses important audio information.
When listening to music we could not achieve a satisfying tonal equilibrium. The bass covers the rest of the frequencies and dominates the scenery; we tried to reduce its volume selectively but we could only wind up with an absent, flat sound. There is a lack of coherence in the middle-low ranges, where there is a hiatus between the inferior middle spectrum and the bass.
As for watching movies and gaming we believed the system performed well, offering an enjoyable experience. The system possesses sufficient power and dynamicity to render a pleasant atmosphere, the spatiality sensation is vivid while the subwoofer raw strength brings in a specifically charming sensation, regardless if we consider a Playstation/PC game or an HD movies.
The use of the ASUS Xonar D2 coupled analogically brings no significant benefits with regard to sound quality, certain details became more present, but to an insufficient extent so as to justify the investment if you own this system.

Z906:
Z906 has an aggressive bass which is lacking precision and depth. There were moments when it sounded uncontrolled, having a tendency towards humming and booming. While watching movies or gaming its swiftness confers a plus to the atmosphere while offering the necessary impact in order to make the listener shudder. Compared to Z5500, the Z906 bass cannot explore the very low frequencies, lacks depth, while being superior both in speed and aggressiveness. For movies and games we preferred a fast bass while for music we considered Z5500s bass to be superior. Similar to Z5500, the subwoofer output has a tendency to cover the rest of the frequencies. However, in order to obtain a correct sound, we could manage a satisfying tonal equilibrium by playing with the system settings (which we could not obtain in Z5500).
The middle-range frequencies are very much similar to the Z5550, present but cold, synthetic, soulless. The only difference we could find between the two systems was a “thicker” sound envelope in Z5500, owed, most likely, to the bass-reflex encasing design.

The absence of dedicated tweeters is the great minus of this system. Despite numerous critiques received along the seven years of existence, Logitech decided to use the same technical solution of a full-range loudspeaker covering middle and high frequencies. We must admit the result is not overly disappointing (as one might expect at first glance), as the sound climbs up quite well in frequency. However we should reformulate two easy to spot problems: the system has an evident absence of details, which if manage to be squeezed out are being constantly covered by bass and middle-range frequencies.
The soundstage is mediocre for both models, a normal thing, considering that none of the two systems was designed for an audiophile stereo performance. As far as grinding is concerned, we have taken the Z906 out of the box and grinded it for 48 hours while the Z5500 had already been grinded for at least one year. We noticed no significant variation after the grinding period, as we listened to the system right after we’ve taken it out of the box for two days without long intermissions.
As with the Z5500, using the analog output of ASUS Xonar D2 brings no major improvement of the sound, so we once again do not recommend purchasing a superior sound source for this system.

We have also performed a novel experiment, coupling both system’s satellites to the massive Onkyo 807 receiver, being curious as to what extent are the satellites limited by the integrated amplifying module. We can sat it came as a surprise to hear the sound getting significantly better even for the untrained ear. The experience was indeed far from what we could easily achieve with our multichannel system based on Warfedale Diamond loundspeakers (which we own), but we could notice a clear quality increase at the level of details and dynamics, so we could conclude that the integrated amplifiers of these systems does not squeeze everything out of their speakers.

CONCLUSIONS:
If one year ago someone would have asked us what we would expect from Z5500’s successor we would have answered “dedicated tweeters, HDMI inputs, and decoders for the new hi-res (DTS-HD and DolbyTrueHD) formats”. Unfortunately Z906 brings NONE of the above mentioned feats, therefore we believe that Logitech missed an important moment, the moment it could have made Z5500’s successor a shining star of the PC/HT dedicated audio systems. On the other hand we suspect that the “lighter” amplifying unit design is meant to make the system more durable than the previous one and thus more appealing. It is thus a more stable, friendlier version of the Z5500 rather than a true upgrade.
PROS:
– Good performance in movies and games
– Good connectivity and versatility
– Slick design
– Competitive price
– Ease of usage
CONS:
– The sound lacks any sort of refinement
– Lack of dedicated tweeters
– Lack of high definition decoders
– Severe lack of improvements compared to its predecessor Logitech Z5500
– Mediocre integrated amplification (bottle-necking the loudspeakers)
– Questionable quality cables (can be fixed)