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Proof of life. [What follows is a one-page interlude describing issues with a defective first sample which were completely resolved. If you wish to skip over it to continue with descriptions of the USB 24/192 and direct-drive features, click here - Ed.] Hostage negotiators always demand proof of life first before their games begin. Taking delivery, reviewers do the same. We report to our senders not just confirmation of receipt. We also report that all systems are a go. Or not. Then we ask for trouble shooting, repair or replacement. Being most curious about the DAC2's USB implementation, that's how I began verification that the loaner was operational. As soon as I selected the Wyred4Sound DAC2 in the sound devices window, the iMac crashed. At least it caused a "you must turn off the computer now by holding down the power button until it turns off, then restart" message. The second time was a go though. Alas now I had massive noise. I could make out the signal but it was deeply buried in 80% static, 20% music. I had lock of sorts but no joy. The USB 192k in the small blue display shoulda tipped me off. After all, I was only streaming regular 44.1kHz CD rips from the iMac. But I didn't catch on yet. I first suspected a wrong driver. I'd installed firmware for OSX 10.6. Checking to be sure, my iMac was indeed running version 10.6.4. One suspect down.

S/PDIF was next. Instead of pulling out one of my legacy spinners however—Ancient Audio Lektor Prime or Raysonic Audio CD-228—I set the iMac's System Preferences - Sound window to my Weiss converter. Now I leashed a Black Cat Veloce S/PDIF cable between it and the Wyred. The Weiss became mere D/D converter between incoming Firewire and outgoing coax. Suddenly Beethoven twitched in his grave. The ode to joy was on. Hallelujah? Not quite. Coax was peaches but USB still massively distorted. (Because Weiss and Wyred4Sound both have named their machines DAC2, I'll refer to the Weiss henceforth as Minerva. That was the sonically identical consumer version after all.)

Avoiding ear pain, I instantly switched back to S/PDIF. Ah, real music again. Now I was convinced that my loaner hardware was fine. It had to be a software issue. Next I accessed the Minerva's OSX setup window. When I switched it from 176.4kHz to 192kHz, the Wyred immediately followed suit. It locked to the new data rate automatically. Running through all the Minerva's options—x 2 and x 4 oversampling with 44.1kHz or 48kHz base lines—the Wyred kept pace like greased lightning. It always displayed the same rate I set the Weiss to. Finally lightning struck upstairs. USB was in the shitter because the Wyred sat at 24/192 yet only received 16/44. Yes? Clueless how I'd gotten stuck with the wrong data rate—Wyred's software options can't change it; the machine doesn't run its own adjustable OSX device window like the Minerva; and I hadn't prompted iTunes to output 24/192 nor played any HD files—I defaulted to Wyred's reset function. Suddenly USB displayed properly as 44k1. Now I had proof of life and the game was on. Incidentally, I never could replicate the problem. I could not identify what had caused the faulty setting in the first place. For me reset was the magic reboot. Problem fixed if not mystery solved.

But - something was still unexpected. While switching the iMac back and forth between Firewire and USB devices, I had noticed how S/PDIF via Firewire was superior. USB by comparison was whiter and bleached. It was more distanced and less robust. It frankly sounded just a bit washed out. Why? The same Sabre DAC handled D/A conversion for either data stream. Unfortunately I could not feed the DAC2 with coax and USB from the same source. With the iMac, coax had to go through the Minerva, USB connect directly to the DAC2. My legacy spinners obviously have no USB outputs. With them I could make comparisons against the Minerva ad infinitum—coax vs. coax—but USB was out. I simply could not determine whether on its own, the Wyred4Sound's S/PDIF input made better sound than its proudly advertised 24/192 async USB socket.

Off went queries to both EJ Sarmento and Daniel Weiss. I wanted to understand what might be responsible for what I heard. Minus different cables (Entreq or ALO Audio USB, Black Cat or Stealth Varidig coax), there were the formats of FireWire vs. USB. Daniel Weiss considers FireWire superior but allows that implemented properly, USB can work as well. To make any proper prognosis between formats, one would at the very least need a converter with async USB and FireWire inputs where both were designed to the same standards. Only that would eliminate extraneous variables. Now Daniel Weiss reminded me. In my particular S/PDIF scenario, Sarmento's converter had to lock to his Minerva as the master clock. The Wyred was automatically slaved. In async USB mode however, the Wyred became master clock to the iMac. So master clock duties between coax and USB were dissimilar. Weiss handled S/PDIF, Wyred USB.

Was I hearing the effects of different reclocking schemes on jitter? If so, the dual phase-lock loop JET implementation of the Weiss was superior. Daniel allowed that " would think the master clock in the final DAC best but as you saw, this is not always the case. I have many comments from pro audio people where converters perform better when synced externally over running from their own internal clocks."

In the absence of an external clock input for the Wyred DAC, I'd inadvertently created one. For S/PDIF from the iMac, I had turned the Weiss Minerva into the system's master clock. While the sonics were brilliant, I felt ill at ease. I had no definitive cause why USB with the Wyred was inferior. I had only reasonable assumptions. Once before I had reviewed an entry-level external master clock by Esoteric connected to one of their better integrated players. Reclocking then had produced no real advantages at all. I'd thus privately concluded that external word sync was perhaps best reserved for transport/converter separates, not one-box machines. Since I'd never tried external clocks with digital separates, I was unprepared for just how this latest comparison suggested that with them—and perhaps particularly with PC 'transports'—reclocking could be surprisingly effective?

Sarmento: "My PC has both coax and USB outputs. When I compare either, USB sounds at least as good if not better. In your case, I agree that we are not comparing apples exactly. But given that the USB feed is I²S straight into the Sabre, I don't see how the extra circuitry of your S/PDIF route could be better. There shouldn't be any improvements possible by reclocking S/PDIF versus the direct USB/I²S feed which is jitter free entering the Sabre DAC. I suspect we might have an issue with the comm link between micro chip and USB transceiver. You did after all experience the initial problem with the wrong data rate. I would like to send you a new cover with the controller circuit mounted to it." Fair enough. I frankly didn't discount the possibility that external reclocking could reap audible benefits, never mind theoretical 'should nots'. Eliminating possible malfunction is simply proper procedure. So a new controller it was.

Hooking up the refreshed unit as the streaming USB client, the iMac again once enforced a manual shutdown. Taking this as a good omen, I restarted. Presto, the Wyred now showed a proper USB 44k1 right off. How about prior superiority of lengthy coax over short USB paths? No more. Now S/PDIF and USB were indistinguishable. EJ's prognosis of a defective controller seemed correct. Reader Philippe from Montreal: "I also have a DAC2 and also had EJ send me a new cover because of volume control issues. As I'm convinced too that you were dealing with software bugs, it would be really interesting to me if you could indicate the firmware version you are now testing (briefly shown when starting up the device from the master power switch). My device is 1.3 now, volume bugs were in 1.2."

A quick check showed my new controller to run v1.4. Sarmento explained the firmware evolution: "v1.1 original production software; v1.2 corrected setup menu max level display; v1.3 added trigger in remote turn-on as an alternative to HT bypass activation and corrected Min level issue when in fixed mode (Min + Max >70 = no sound); v1.4 some changes to the volume control timing so it would ramp up smoother (it seemed to operate with slight pulses before)."