October 2010

World Premiere!
Silicon Arts Si2 Micro Integration Line Preamplifier, Amplifier And DAC
Child prodigies that pack a significant sonic wallop!
Reviewed By Dick Olsher
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  The proverbial "good things come in small packages" very much applies to Silicon Arts' new micro line. And I do mean a small package. Each chassis is nominally 4 x 4 x 2 inch. The Si2 line represents a minimalist and affordable response to the bloated designs being hatched routinely in the ultra high-end arena. It's questionable whether excessive complexity serves the music, though it definitely drives prices up. Designer Tsuda-san's design philosophy has steadfastly been focused on minimalism, parts quality, and circuit layout.

The question being addressed here is how much chaff can be peeled off typical high-end components while still retaining perhaps 90% of the sound quality. Gone is the fancy chassis, overkill power supply, and circuit complexity. What remains encapsulates Silicon Arts' magic in a trio of components (DAC, line stage, and power amp) priced within reach of the common man. In the United States, the exclusive retailer is Eastwind Import, an online music and audio shop. This is a more direct path to the consumer which is also responsible for keeping the pricing structure where it is.

Technical Details
Size does have its limitations when it comes to power output, unless one goes the route of Class D amplification. The Si2 chassis is too small to accommodate a large number of output devices and heat sinks. The Si2 power amp is necessarily low power (10 wpc into 8 Ohm). Therefore, one possible application is in the context of a multi-media system where you are pretty much on top of the speaker. Proximity overcomes a speaker's low sensitivity. Listening at 2 feet versus 10 feet would make that 10 wpc amp behave more like a 100 wpc amp. Of course, another perfectly normal application would be a high-sensitivity speaker with a minimum sensitivity of around 95 dB. I'm told that in Japan, the Si2 line is popular among audiophiles who use high-efficiency, single-driver loudspeakers. The bulk of my listening impressions, and certainly all of my time with the Si2 amp, were in the company of the Basszilla Platinum Edition Mk.2 DIY speaker. A 96dB/W/m sensitive speaker is just right for the job at hand.

Another concession due to size has to do with the power supply. All of the Si2 models use an external universal AC/DC power adapter. The line stage and DAC are powered off 12VDC/300mA wall warts. However, the power amp is outfitted with a substantial switching type 70W power adapter rated for an output of 12VDC/6A.

The amp's output devices are operational amplifiers (op amps) operated in Class AB. There is a total of four devices. Each pair is connected in bridged mode (so called bridge-tied load or BTL) in order to increase the voltage swing and current drive into the load. Still, a minimum load impedance of 4 Ohm is a sane lower limit. The circuit topology is similar to that used in the flagship ZL-120 power amp. The power amp gain is set relatively high at 32 dB, which means that line-level inputs don't really need any additional gain at the preamp.

Not surprisingly, the Si2 line stage has zero gain. There are two line inputs, selectable from the front panel. Input switching is performed electronically, as is the case with the far more expensive Concert Fidelity CF-080. An electronic volume control is used, similar to the one used in the CF0-80, although there is no level display which makes it difficult to reproduce a particular volume setting. The printed circuit board is mounted on the rear panel keeping the signal path to just about one inch. Tsuda-san says that his design goal for the line stage was to exceed the level of purity, openness, and transparency set by passive attenuators.

The DAC uses a Cirrus Logic 192 kHz S/PDIF CS8416 receiver chip. However, the DAC chip is the old reliable dual 16-bit Philips TDA1543 used in non-oversampling mode. This R2R multi-bit DAC type, despite being 20 years old, is well suited to zero oversampling applications and more than holds its own relative to most recent sigma-delta chipset based designs. Zero is still my hero! Zero oversampling that is -- think of it as a digital nasties repellant. If you've read my review of the Concert fidelity DAC-40, a winner of our "The Best Of 2009 Awards," then you should have a better idea of why I consider zero oversampling designs to more closely approach the analog experience.

The Sound
I introduced the Si2 components into the reference system one at a time in order to obtain a handle on each component's sonic signature. Although they are all good, the real star turned out to be the power amp. One of the attributes I look for in a power amp is its ability to preserve what comes before it in the signal path. Mated with the Mystère CA21 tube line preamp ($2195), one of my favorite line stages under $5000, I was curious to see just how much tube magic the Si2 amp would allow to shine through. My fear was that the CA21's considerable tube virtues would be diminished by an overbearing solid-state personality. The end result was an emphatic wow! It was all there: a spacious soundstage, sweet mids, and remarkably liquid harmonic textures. And that's not all: it was able to elicit satisfying rhythmic drive and microdynamic intensity -- a boogie factor uncommon for a solid-state device.

Some of its performance aspects very much reminded me of the ZL-120's sonic character. In particular, excellent transient speed and control, and a level of soundstage transparency I have come to associate with far more expensive power amplification. It was oh so easy to connect the dots, if you will, and peer deeply into a cohesive and spatially 3-D soundstage. Low-level detail was retrieved naturally without etching of the treble range. In general, timbre accuracy was quite convincing. I would characterize bass definition as an 8 out of 10, as it was fairly convincingly able to distinguish between Fender bass and an upright bass playing in unison. However, bass impact was a bit restrained while trying to reproduce loud tympani drum strikes.

At this point, I was very curious to trot out one of my favorite low-power solid-state amps for a comparative listen. The First Watt F3 (15 wpc into 8 Ohm), designed by Nelson Pass, is a simple single-ended Class A design which uses power JFETs and touts exceedingly low distortion figures. It became clear that the F3 possessed a more potent low end. But, and this is a significant caveat, the F3 sounded much less spacious relative to the Si2 as image outlines assumed a more 2-D posture. This is an especially important finding for the tube crowd. If you're into tubes, then obviously soundstage dimensionality is an important priority, and it's good to know that with the Si2 it's not lost in translation. There was also no way around the fact that the F3 was sounding a bit grainy, in stark contract with the pure and liquid textures of the Si2. Why that should be is a bit of a mystery considering the F3's purist design. Nonetheless, the indisputable conclusion was that the Si2 amp was far more tube like, and that's very good news for tube aficionados looking for solid-state amplification that does not sacrifice tube values in the mindless pursuit of low-level detail.

The Si2 preamp turned out to be a far better match for the Si2 amp than it was for the F3. Image outlines were not as palpable as with the Mystère CA21 but the Si2 amp's virtues remained essentially intact. Although not nearly as liquid as the CA21, the Si2 line preamp impressed with its excellent soundstage transparency and retrieval of low-level detail. Mated with the far more expensive Berning ZH230 tube amplifier, it acquitted itself pretty well with good command of microdynamic nuances. This coupling was designed to give the Si2 preamp a chance to sink or swim in the context of an ultra high-end system. It didn't exactly sink, but harmonic color saturation was only fair and the lower mids lacked the big tone character of the 6SN7 based CA21. Back it went to driving the Si2 amp, but even here I missed the vivid colors and tonal authority of the CA21. Near a system's front end is where tubes are needed most for a dose of tube magic. Why not combine the electronic volume control with a tube-based buffer stage? Now that would be a product I would be most curious to audition. How about it, Tsuda-san?

The Si2 DAC needs to be positioned near the preamp due to its highish output impedance. It can't drive long interconnects. Short is good, up to a maximum of one meter. Its presentation is pure and clean, and most importantly, devoid of upper register brightness -- a.k.a. digititis -- that gave rise to digital phobia in the 1980s. The problems of analog brick-wall filters and jitter are so well known by now that you'd think that modern CD players and DACs would sound uniformly excellent. Sadly, that is not the case. After so many design iterations, receiver and DAC chipsets excel on the basis of specifications, offer the convenience of oversampling, digital filters, and low prices driven by mass production. With all of this technology at their fingertips, how can so many designs get it wrong musically? To its credit, the Si2 DAC gets a lot right. It made a strong analog-like impression with its firm portrayal of the soundstage. Image outlines were solidly anchored within a spacious soundstage. It worked well with the Si2 preamp to maintain excellent soundstage transparency. I suspect that it is best suited for use with bright speakers, a context within which it should provide a perfect antidote since it sounded a bit laid back and darker than the real thing. In addition, it fuzzed over some low-level detail. So if detail retrieval is a major priority for you, then this DAC certainly would not be your best choice. On the other hand, it is eminently listenable -- a priceless quality for long-term musical enjoyment.

Conclusion
Don't let their size fool you. The Si2 micro line components could best be described as Silicon Arts' child prodigies, packing a significant sonic wallop. The real star, however, is the Si2 amplifier. It is a finely faceted sonic jewel that emphatically raises the performance bar for low-power solid-state amplification.

Specifications
Power Amplifier
Power output: 10 wpc into 8 Ohm; 14 wpc into 4 Ohm
Gain: 32 dB
THD: 0.02% at 4 watts
Dimensions: 106mm(W) x 45.6mm(H) x 110mm(D)
Weight: 1.5 lbs
Price: $1420

Preamp
Inputs: Two line-level inputs, single-ended (RCA)
Outputs: 1 pair, single-ended (RCA)
Gain: 0 dB
Attenuation Range: 0 to -79dB
Signal/Noise Ratio: >100dB
Stereo Separation: >100dB
Dimensions: 106mm(W) x 45.6mm(H) x 110mm(D)
Weight: 1.75 lbs.
Price: $1580

DAC
Inputs: 1 digital input (S/PDIF), single-ended (RCA)
Outputs: 1 pair, single-ended (RCA)
Dimensions: 106mm(W) x 45.6mm(H) x 105mm(D)
Weight: 1.2 lbs
Price: $1260

Company Information
Silicon Arts
United States Distributor: Eastwind Import

Voice: (714) 334-0759
E-mail: sato@siliconarts.jp
Website: www.eastwindimport.com