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Equipment Review

November 2002

Zanden Audio Model 600 Integrated Amplifier

by Doug Schneider


Review Summary
Sound "Quick, agile, and incisive -- surprisingly so for a tube-based design"; also a "substantial and weighty soundfield with good articulation that gives a recording scale and lets it occupy a large space in the room."
Features "Uses four triode-connected KT88 output tubes in a push-pull configuration" to deliver 30Wpc; "no biasing is needed because the Model 600 uses Zanden's 'JPN patented fixed-bias technology.'"
Use No remote control -- "meant for listeners who eschew gadgets and simply want to turn it on and play music with a minimum amount of fuss"; sounds its best after 15 or 20 minutes of warm-up.
Value "The Model 600 integrated amp is an outstanding way for the everyday audiophile to enter the once-exclusive world of Zanden Audio."

Japan is well known for producing top-notch, cutting-edge products of all types, including, obviously, audio equipment. However, in the audio world, Japanese firms aren't often associated with state-of-the-art-chasing vacuum-tube designs. I didn’t make the connection -- until some Zanden Audio products made their way to my door.

Zanden products are splendors of style -- compliments of Zanden owner and head designer, Mr. Yamada Kazutoshi. With their spare-no-expense appearance, they’re the kind of components that you want to place front and center in your listening room. One friend said to me about the Model 5000 Mk II DAC, "I just want it for the way it looks!" And the circuitry? Distinctive to say the least. Once again, look no further than the 5000 Mk II: It has no oversampling or upsampling and uses pure 16-bit DAC chips! That’s Mr. Kazutoshi and his unique view on how audio equipment needs to be designed to communicate the musical message. Zanden Audio products have style and substance -- the 5000 Mk II DAC is simply one of the best digital products I’ve heard.

But there’s been one catch to the Zanden Audio line: until now, the products have been prohibitively expensive. The 5000 Mk II, for example, is $9800 USD. Zanden amplifiers are far past $10k. Zanden Audio has always been destined for a rather exclusive crowd.

Enter the 100-series products -- Zanden ideas brought down to a price more people can afford. The $4500 Model 600 integrated amplifier is the first in the series, and the company says that in time we’ll see a DAC too.


Pictures don’t do the Model 600 justice. First, it’s larger than it appears in photos -- measuring about 17"W x 6 1/4"H x 14 1/4"D and weighing 44 pounds. Second, it’s better-looking too. The 600’s polished stainless-steel chassis shines brilliantly with the Zanden name shown prominently on the front left. The cover -- cleverly swooping down across the front and around one side -- contrasts wonderfully. The 600 doesn’t quite have the beauty of the far more expensive Model 5000 Mk II DAC -- that piece has an almost sculpted appearance -- but it has that same Zanden sex appeal and embodies the commitment to producing something aesthetically and sonically pleasing.

The Model 600 uses four triode-connected KT88 output tubes in a push-pull configuration -- a departure for Zanden because the company's more expensive amplifiers are single-ended designs. The gain stage uses four EF86 tubes. The rectifier section has one 6X4 and two 5AR4 tubes. No biasing is needed because the Model 600 uses Zanden's "JPN patented fixed-bias technology." Power output is said to be 30Wpc, and the company says that the Model 600 is suitable for speakers with a 6-8-ohm nominal load.

The Model 600, like the other Zanden components, is a minimalist design -- meant for listeners who eschew gadgets and simply want to turn it on and play music with a minimum amount of fuss. There are three knobs for operation -- increasing in size from left to right, a subtle touch that adds to the 600's elegant appearance -- and no remote control. The left-most knob turns the Model 600 on and off. The middle, medium-sized knob is the input selector -- the four red LEDs above it indicate which input has been chosen. The right-most knob is the volume control (the volume pot itself is by ALPS).

The 600 is simple to operate, but I do have one little gripe about the volume control: Except for an extremely small screw at the very back of the knob, it doesn’t have any line on it or other marking to let you know where it is turned to. A little too minimalist? Perhaps. I made it a good practice to turn the volume all the way down each time I powered the amplifier up and started playing music to ensure I didn’t blast anything from the room.

On the back toward one side is a vertical array of line-level input jacks labeled "cd," "phono/line," "tuner," and "aux." The input connectors are the same heavy-duty, slightly recessed jacks that are used on the Model 5000 Mk II DAC. Across the bottom middle are high-quality WBT speaker-cable binding posts. On the other side of the back panel is the IEC receptacle for a detachable power cord.

Given the Model 600's large size and the fact that it is a minimalist piece with only a limited number of input and output connectors, everything is well spaced, with plenty of room for even the most unwieldy of cables.

System and setup

Components used with the Model 600 were the Zanden Audio Model 5000 Mk II DAC, being fed bits by my trusty Theta Data Basic transport and connected via an i2Digital X-60 digital interconnect. Cabling was all Nirvana S-L series. Speakers were Song Audio Type II Silk DM and Ruark CL10.

You don’t buy an amp such as the Model 600 for its power output; similarly priced solid-state amps have many times this one’s output capabilities. And you don’t buy it for features, either; lowly integrated amplifiers and receivers today have many times the number of controls and doo-dads on them. Instead, you buy the Model 600 for the way it sounds and to some extent for the way it looks. So, if you like what the 600 does and you want to go this route, then you have to take a bit of care in terms of picking speakers for use with it. After all, it does only output 30Wpc. But don’t let this scare you -- 30Wpc is actually plenty of power for many listeners.

There’s a bit of a myth in terms of how much power a system needs. The truth of the matter is, not much for average listening levels with speakers of average sensitivity. The full output of high-power amplifiers is often only called into service on rare occasions -- when someone needs to play things really loud or when speakers are insensitive. During normal listening, the number of watts an amplifier puts out is usually in the single digits -- even with speakers of only average sensitivity. Some people do need high-power amplifiers; but in my modest-sized room, using speakers of only average sensitivity, I never came close to taxing the Model 600.

So, if you’re like me, don’t necessarily think that you have to have a supposed "high-sensitivity speaker design" in order to use this amp. In fact, that’s a bit of a myth too. There are very few true high-sensitivity speakers on the market, despite some companies’ claims. If a speaker is a true high-sensitivity design, it will generally use horns or employ some sort of unusual technology. If it’s not a horn design and, in fact, looks pretty much like most other loudspeakers (average-sized woofer and a tweeter in a regular-sized cabinet), then you should start asking questions about how sensitive it really is (or, perhaps, start running for the door).

To learn about speaker sensitivity, simply do some research -- and a good place to start is with our own speaker measurements, done independently at Canada’s National Research Council using precision measuring equipment and a real anechoic chamber. They’re accurate, they’re objective, and they tell an amazing story -- oftentimes contradicting marketing literature. And if you look through them you’ll see that speakers that have sensitivity above 90dB (with a 2.83V input) are rare.

We measured the Song Audio Type II Silk DM and the Ruark CL10, and their sensitivities are 89.5dB and 86.5dB respectively. Listening levels of 85-90dB are pretty respectable -- and you need only a watt or two to get there. Getting up to 95dB is a snap with an amp such as the Model 600. And you can see that with true high-sensitivity speakers, prodigious output levels can occur with only a whisper of power -- although, obviously, I never had a speaker like that around. Take note, though, that sensitivity is only one part of the equation; there are other considerations, such as impedance -- the load the speaker presents to the amplifier (the lower the number, the more difficult the speaker is to drive). So, for example, even if a speaker is 95dB sensitive, a 3- or 4-ohm load would likely render it incompatible with some amps because it’s exceedingly difficult to drive. Tube amps specifically don’t like loads as tough as that, regardless of how sensitive the speakers are. Both of the speakers I used stay mostly above 6 ohms, making them fairly easy to drive.

The Model 600 powers on gently, beginning with a mute cycle that allows the circuitry to start up safely before delivering power to the speakers. Once ready, the Model 600 operated with a light hum that could be heard when standing close to the unit, but it was not detectable from the listening chair and was masked completely when music started playing.


Although the Model 600 is operational in a number of seconds, I found that it did not sound its best until it had been warmed up for 15 or 20 minutes -- likely to get the tubes and circuitry up to a proper operating temperature. Once to that point, the Model 600 delivers a rather bold and majestic presentation with great transparency.

Tupahn is a street musician who plays locally here in Ottawa from time to time. Relying on only his electric guitar, he can draw an impressive and appreciative crowd as he churns out his versions of well-known classics. His self-produced CD called Covered Treasures [no catalog number] has all of his "street" songs. It’s worth the price I paid just for his cover of Paul Simon’s "The Boxer." The disc opens with "Whiter Shade of Pale" -- recorded with a vibrancy that gives Tupahn's guitar real weight and substance. The 600's bold presentation made the instrument resonate with vitality that made it seem alive. But the guitar wasn’t just robust-sounding; it was transparent too, and I was struck by how lively and dynamic the 600 sounded despite its modest power rating. The Zanden-based system sounded so transparent and natural that it helped create the illusion of a live musician, one I've heard numerous times, in my room.

Tupahn’s playing is unpredictable, going from slow to a high-speed flurry in a flash. The Model 600 is quick on its feet and captures each nuance with precision. When the guitar string is plucked, you can sense the weight and hear detail as it sprinkles off the guitar. The 600 sounds quick, agile, and incisive -- surprisingly so for a tube-based design -- and I suspect this is precisely why it gives such a transparent view to the recording and such a feeling of being alive. And like the Model 5000 Mk II DAC, the Model 600 is immediate-sounding -- it puts the musicians there -- and that makes it sound so full and natural.

The 600’s resolution is quite high -- not to the point of hearing dust falling in the studio, but sufficiently so to allow you to quite easily hear the air around the instrument and the space of the recording venue. The result is a substantial and weighty soundfield with good articulation that gives a recording size and lets it occupy a large space in the room. After finishing Tupahn's disc, my reaction, written down, was "Yowza, this amp sounds real!"

Mark Knopfler’s new A Ragpicker’s Dream CD [Warner Brothers 48318] is wonderfully recorded. In particular, the vocals sound quite stunning at times, and the opening track, "Why Aye Man," really shows how the 600 shines in the crucial midrange. Knopfler’s textured voice is rendered with such presence that it can raise goose bumps. Ultimate power and bass may not be the domain of tube amps -- something I’ll get to in a bit -- but a majestic midrange sound that has presence, loads of detail, and a wonderful sense of liquidity and ease is. And even with real in-your-face vocals -- Bruce Springsteen’s The Ghost of Tom Joad [Columbia 67484], for example -- the Model 600 doesn’t overdo them and make them sound too forward or too warm and robust. The 600 has a rather grand sound, leaning to the side of being warm, but it’s also quite detailed and has the immediacy I keep coming back to. In fact, that combination of liquidity and immediacy that both the 600 and 5000 share is something I’m beginning to think is a trademark of Zanden Audio sound.

As for bass, first let me tell you that no tube amp I’ve heard is better at going low than the best solid-state amps. But if you’ve been around the audiophile block, I’m probably not telling you anything you don’t already know. The midrange may belong to tubes, but the bass belongs to solid state, and it’s a snap to prove.

I’ve played the same Knopfler track with the $4800 Orpheus Three 40Wpc solid-state power amplifier and the same speakers. The Three is a muscular little bugger despite its relatively low power rating, and it has a vise-like bass grip that a tube design such as the Model 600 can’t match. Ask for great bass and you’ll be steered to solid-state amplifier names like Bryston, Mark Levinson, Krell -- and now, quite likely, Orpheus too.

On the other hand, the 600 is certainly no lightweight down low, and there’s more to good sound than simply seeing if something can crack the concrete. No, the Model 600 is certainly not as "through the floor" as the Orpheus; instead, it’s a little more round and in ways just as full-sounding in the sense that there is more bloom to it. It’s a bit of an apples and oranges thing -- the Three being ultra-tight and deep, the 600 a little more generous and rich. But before you get the wrong impression, understand that when I mention these characteristics, they are not intended in the way that some still think about "tube-amp bass" -- fat, lazy, and out of control. That’s old-school thinking, and the 600 isn’t a student in that class. The 600's bass is tight, tuneful, and deliberate -- just not to the same level as an amp such as the Orpheus Three.

Then there are the highs, and this area, like the bass region, makes solid-state to tube debate an apples-and-oranges thing again. Today you can get a great solid-state amp that will have a top end that extends to the stratosphere -- enough to drive dogs crazy and perhaps crack glass. I doubt very much that the 600 can extend that far. But don’t get the idea that its sound is rolled off or anything like it. In fact, I was surprised at just how much treble extension the Model 600 possesses. It gives all the detail needed up top, but its strengths extend beyond -- there’s crystalline purity and reach-out-and-touch firmness that can be heard when the wood of a drumstick hits the metal of a cymbal or fingers pluck the strings of a guitar. The result is a tangibility to the sound that is startlingly real -- and again this is just like the Model 5000 Mk II’s performance. Witness Tupahn’s brief frenzy on "Whiter Shade of Pale" -- one of those flurries that goes from sleepy to ecstatic -- and you’ll hear how precise and vivid the 600 sounds up top. Listen also to Norah Jones’ piano on "Shoot the Moon" (Come Away with Me [Blue Note 32088]) and you’ll hear bell-like clarity along with a bit of fullness that I simply don’t get from the top ends of many solid-state amps, despite how far they can extend into the stratosphere.

Finally, we come to imaging and soundstaging, an area that is affected most by speakers and placement, but also to a degree by the components in front of them. The fullness and texture inherent in the 600's sound transfers into a soundstage that is dimensional and, as some like to say, palpable -- meaning fleshed out in a way you can almost touch. Voices pop out and occupy space that has size left to right and front to back. The Model 600 is just a little forward, so with either the Jones or Knopfler discs, the voices generally get launched just a bit in front of the speaker plane -- a characteristic I find exceedingly desirable.

Depth of stage, when it’s present in the recording, can be quite rewarding, with vocals and instruments such as guitars far up front in the mix and other instruments such as drums fairly far back. And with resolution, which I already mentioned is quite high, nuance and detail are easy to hear, and this allows you to get a good sense of the recorded space. The Model 600 more or less blossoms in your room.

More comparison

First, talking tube to tube, most certainly there are other tube-based designs that have the qualities the 600 has and then some. A while ago I had Wyetech Labs’ 211-based Topaz amplifier in here -- 18Wpc of pure class-A, single-ended magic at just a smidgen under $10k -- and that’s precisely the amp the Model 600 brings to mind. The Topaz, though, sounded so pure in the mids that it was as if it was not even there. Transparency and presence, it had it all -- except equal power, as it was rated at almost half what the 600 is. But some people swear by single-ended designs, and my sonic experience with the Wyetech amp had me thinking they may well be right. In fact, Zanden’s best amps are single-ended designs -- and a whole lot more expensive than the Model 600.

But are amps like those perfect? No -- but remember, nothing is. Line one of those up against a good solid-state amp and you’ll still be left with the same criticisms I mentioned earlier, if not more of them. Generally, single-ended designs have even lower power output, and speaker matching becomes even more of a concern -- to the point of really being a concern. Quite simply, when you spend more money in the tube world, such issues don’t get fixed as they do in the solid-state world, where more money usually equals more power.


When I received the Zanden Model 5000 Mk II DAC, my eyes were opened to a different kind of company -- one that values high style and wonderful sound, oftentimes using technology that’s downright surprising. The Model 600 simply carries on this tradition, albeit at a much lower and more affordable price.

Am I impressed with the 600? Certainly. In fact, when the Model 600 arrived, I was told that the tentative price was about $6000. For months I used the 600 under this assumption and came away with the impression that, given the stellar sound I described along with outstanding cosmetics and excellent build quality, Zanden was pricing the 600 attractively enough to call it a good value for discriminating audiophiles who want to own a rather exotic piece of equipment. Later, near the end of the review period, I was told by Zanden that the price was finally set -- at $4500. As you can imagine, my enthusiasm increased -- a lot. The Model 600 integrated amp is an outstanding way for the everyday audiophile to enter the once-exclusive world of Zanden Audio.

...Doug Schneider

Zanden Audio Model 600 Integrated Amplifier
$4500 USD.
Warranty: Two years parts and labor (90 days on tubes).

Zanden Audio Systems Ltd.
6-6-2-101 Shinmori Asahiku
Osaka-City Osaka, Japan
Phone: +81-6-6185-0404
Fax: +81-6-6185-0405

Website: www.zandenaudio.com

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