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Reviewer: Srajan Ebaen
Source: Zanden Audio Model 2000P/5000S
Preamp/Integrated: ModWright SWL 9.0SE; AudioZone PRE-T1 [on review]; Music First Audio [on review]

Amp: 2 x Audiosector Patek SE run one channel each, the other shorted out; Canary Audio CA-308 [on review]; Fi 421A [on review]; Yamamoto A-08S [on review]; WRAD 300 [on review]; Hyperion HT-88 [on review]
Speakers: Zu Cable Definition Mk 1.5; Gallo Reference 3;
Cables: Zanden Audio proprietary I²S cable, Stealth Audio Indra (x2), Zu Cable Ibis, Zu Cable Birth on Definitions; Crystal Cable Reference power cords; ZCable Hurricane power cords on both conditioners
Stands: 1 x Grand Prix Audio Monaco four-tier
Powerline conditioning: 2 x Walker Audio Velocitor S
Sundry accessories: GPA Formula Carbon/Kevlar shelf for transport; GPA Apex footers underneath stand, DAC and amp; Walker Audio SST on all connections; Walker Audio Vivid CD cleaner; Furutech RD-2 CD demagnetizer; WorldPower cryo'd Hubbell wall sockets
Room size: 30' w x 18' d x 10' h [sloping ceiling] in long-wall setup in one half, with open adjoining living room for a total of ca.1000 squ.ft floor plan

Review Component Retail: $1,750/pr

After publishing the following two pages, the manufacturer expressed unhappiness with my approach and I cancelled the review. What follows is thus merely a product description and some technical background on the early development challenges of USB audio. For those interested in the latter, we've left these pages up. Those expecting full-blown performance commentary won't find any here and will prefer to google reviews of this product elsewhere. - Ed.

The Universal Serial Bus isn't a shuttle on a movie studio or a hippie cereal supplier. No, USB is the now ubiquitous high-speed computer peripheral interface whose newer v2.0 is 40 times faster than the original v1.0 - 480MB/sec to be precise. Controller chips by Philips, NetChip, SourceForge and others handle the bidirectional communications. The operating system auto-detects a new device upon initial connection. If the device has been preinstalled, the computer activates it. If not, it'll ask for a driver disc. USB devices are hot-swappable and can be connected and disconnected at any time. Many USB devices can be put to sleep by the host CPU when the latter enters power-saving mode.

When the host powers up, it queries all of the devices connected to the bus and assigns each one an address. This process is called enumeration. The host
determines from each device what type of data transfer it wishes to perform: Interrupt (a device like a mouse or a keyboard, which will be sending very little data); bulk (a device like a printer receives data in 64-byte chunks) and isochronous (for streaming devices such as speakers and DACs). In the latter mode, data streams between the device and the host in real-time without error correction.

The host can also send commands or query parameters with control packets. As devices are enumerated, the host keeps track of the total bandwidth all isochronous and interrupt devices are requesting. Those may consume up to 90% of the available 480Mbps bandwidth. Greater draw means the host denies access to further devices. Control packets and packets for bulk transfers use the remaining bandwidth (at least 10%). USB divides available bandwidth into frames and the host controls the frames. Frames contain 1,500 bytes and a new frame starts every millisecond. During a frame, isochronous and interrupt devices get a slot to guarantee their bandwidth. Bulk and control transfers use whatever space is left.

So-called USB hubs expand the number of available slots on your computer should the number of devices you wish to connect outnumber your preinstalled USB terminals. Powered hubs include their own transformer to avoid overloading your computer's power supply. A USB cable has two wires for power (+5 volts and ground) and a twisted pair to carry the data. On the power wires, the computer can supply up to 500 milliamps of power at 5 volts. Low-power devices (such as mice) can draw their power directly from the bus. High-power devices (such as printers) have their own power supplies and draw minimal power from the bus.

USB has become the preferred link over serial and parallel ports and requires no add-on cards. USB can connect up to 127 devices to a CPU such as printers, scanners, mice, joysticks, digital and web cams, modems, telephones, zip drives, network hubs, scientific data acquisitions devices... and speakers and DACs. Aha. You were beginning to wonder about audio. That equation is simple. Hard-drive + outboard DAC linked via USB = error-free digital front-end. Yes, no S/PDIF error correction is involved. This theoretically makes for a superior combination over even the costliest traditional transport slaved to a DAC plus external reclocker. Naturally, we're talking uncompressed audio files and an audiophile-grade DAC, not MP3 and mickey-mouse converters.

To test this claim (can such a CPU-based front-end compete with or outperform a top-notch traditional audio equivalent), Gordon Rankin of Wavelength Audio had dispatched his USB DAC called the Brick (he makes two more upscale versions of USB-enabled DACs) and a MAC G4 Mini complete with keyboard, mouse, screen, 1GB of RAM and preloaded music. Going MAC was claimed to avoid the quality degradation inherent in the Windows interface. Being a Windows man, temporary MACdom promised to be interesting.

The Brick -- as well as its more upscale Cosecant and Ultimate DPU brethren -- use the same USB interface and multi-bit DAC in the zero configuration (i.e. passive I/V, zero up/oversampling, zero filters).

The Brick's power supply is "a high quality custom wall wart" whereas the dearer models go more custom and then outboard on the supply.

"The Brick uses a 12AU7A tube reactor/choke-coupled instead of the parafeed transformer-coupled output of the Cosecant and the Ultimate. All USB DACs use custom MagneQuest magnetics.

Unlike the Ultimate and Cosecant which add gain after the converter, the Brick runs its multi-bit DAC voltage 25% higher and requires no additional gain stage." [Output is slightly lower than the industry-standard 2V - Ed.]

Pricing along the line jumps from $1,750 for the Brick to a blinding $17,500 for the Ultimate DPU done up in silver.

About USB's advantage over S/PDIF? The latter is unidirectional. USB is not to insure that the data on the hard-drive is identical to what streams out. According to Gordon, "the USB interface is asynchronous to avoid the clocking problems of S/PDIF. The Brick tells the computer it can do 16-bit audio at 32K, 44.1K and 48K. Since the USB receiver only has to handle these 3 frequencies, the clocking to the separate DAC IC has almost no jitter. S/PDIF actually has to be sync'd to the exact frequency of the transport (i.e. if the transport is working at 44.0896K instead of 44.1K, the DAC has to sync to that frequency). Therefore, the jitter problems of S/PDIF almost vanish using USB. With USB, we have a zero error protocol to link the computer to the DAC and very low jitter."

How do we implement it? "The Brick is not a combination single IC USB DAC like many of those which use inferior SigmaDelta DAC output conversion. The Brick uses a multi-bit DAC IC with a single resistor for passive I/V conversion because only a resistor can be a linear device over the entire audio band." It's Gordon's USB controller straight to the Philips TDA1543 chip via (hard-wired) I²S. "The CPU tells the USB controller that the system is active which wakes up the tube output. When the computer is off or in sleep mode, the USB controller turns off the high-voltage section and tube filament."

Would my mighty Zanden Audio 2000P/5000Sig combo - er, shit bricks when faced by the brick? Let's find out. But first, the obvious: The Brick is USB only and thus won't work with regular transports (though what constitutes "regular" may, one fine day a few years hence, do a one-eighty). Accordingly, whatever you want to listen to must first be ripped to your hard-drive, preferably using EAC as described in detail by Marja & Henk. Do you really want to entrust 2000 CDs to the vagaries of hard-drive crashdom? Of course you make a back-up. Touché right on my tush. But - how much time do you have to transfer all your tracks to CPU, friend?

We now interrupt our regular program for a word from our sponsor: "Greetings. I attended the AES (Audio Engineering Society) convention today, covering it for the Grammies Recording magazine. The Javits Center in midtown Manhattan was chock-full wall-to-wall with pro audio gear and lemme tell you - it dwarfed the Stereophile show at the Hilton. This was all future technology, hard drive recording and digital software, though Telefunken was there with an old VW van and refab models of their famous U47 mics and newer models.

Anyway, I was there to cover a panel titled "Death of the Record Business, Rebirth of the Music Business." Opening statements by Bob Ludwig, George Massenberg and some label honchos all amounted to the same thing: The CD is dead. It's all about distribution of new digital formats, namely downloading and file sharing. A couple of people mentioned SACD and DVD-A but for this crowd -- the ones who actually record and distribute the music -- the CD is over. One person even said she had sold all her CDs and only kept copies on her computer as tunes on iTunes. So while we are all pondering which player to buy, the rest of the world is dumping their plastic.

Dinosaur. And damn glad of it. Micallef. Ken Micallef."

Properly castigated by our own staffer, we now return to our regular programme - outdated information for audiophile fossils. Hey, if the distribution format of music has changed -- and who could doubt that we're in the midst of it -- then complaints about how music is delivered are at best quaint and at worst stupidly backwards. That means, a no-compromise USB DAC (with triode) using a proprietary controller isn't an oddity for a few forward-thinking with-it 'philes but a harbinger of things already here in full force.

And that means we better pay attention to it since the survival of HighEnd audio will depend on the hip young generation of downloaders and file-sharers. They'd get the Brick in a heart beat if demo'd to - and if it demonstrably kicked butt over whatever they're currently using (which, if a boom box or equivalent, could be questionable). Let's leave the ifs, buts and wherefores to the pundits for now and listen to this thing, shall we? Soon -:)
Added the designer: "Most 2.0 host controllers have isochronous channels that are programmed so that the host CPU does not get involved. There is also async mode and 2 others which are not supported at this time. All of my products have deep memory to allow for better system interfacing and will work async or iso depending on what the operating system supports. Most OS right now only support the iso. I have included on my USB page a PDF with information about PCs and MACs under $1250 that beat most $10K transports.

Basically the problem with PCs aroused in XP (I think this is when it started or maybe in a later version of Media Player) is the Kmixer. The Kmixer looks at the audio output and determines the highest rate. Then it automatically (even if it is 1:1) upsamples any sample output to USB to the highest rate (48/16 for my stuff). You can use ASIO4ALL with applications like Meedio, Foorbar and other front end programs. This will bypass the terrible Kmixer to result in superior output signal."