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Without isolating built-in D/A converter stages, the DIA-250 outdid the minty one on embodiment, juiciness and midbass spunk before the Stradas hand over to their matching TR-3D subwoofer firing sideways beneath the desk. Embodiment meant more weight and mass on the dynamified half of the electrostatic Gallo equation. But—and this was the decisive difference to the 400—it didn't cloud fine detail and layered depth. The far-spread noise of audience applause following Sting's "All would envy" from Live in Berlin thus retained its percussive elements and with it the sense of 'multi-paralleled' sources rather than stepping down into one big composite facsimile. Anthony Gallo has championed Spectron class D amps for years. Now the DIA-250 confirmed built-in happiness with apparently overkill power from switching transistors.

The Gato also enhanced the Wyred4Sound's dryness with a slightly more voluptuous sense of tone. Because the Strada II is such a fast hyper-dialled creature, it welcomes some amp-delivered fleshiness. But the very same speed and articulate enunciation mind when you cross the line and overdo it. Then finesse bloats into something fatter and less specific. Here the DIA-250 surprised all the more because at-ear SPL at less than one meter obviously draw less power than a big-room setup would. As a low-power aficionado I had to admit that despite its stacked power rating the DIA-250 wasn't lumbering but sufficiently quick on the draw to make the Gallo shine and sound even more full-range on its own. The Polish Superioro widebander from Eryk S. Concept responded just as favorably. Clearly the DIA-250 had taken enough first-watt lectures to heart to be equal to the task.

Unlike the Sabre-powered AURALiC Vega and Burson Conductor, Gato's coax input also played nice with Cambridge Audio's digital iPod dock. Its S/PDIF stream purportedly is too stuttery for the finicky ESS silicon to digest without dropouts. With the Gato it was smooth sailing to the horizon. Ditto the AK-100. Its micro SD-card memory scheme makes for a superior transport to Apple's spinning disk. Be sure to defeat its EQ feature however. It colors the digital output. Streaming a really well-done production like Tanja Tzarovska's lushly layered No Record of Wrong (click here to audition it) makes you question self-righteous audiophile hate for such battery-powered portable solutions. With its 24/192 readiness the $699 Astell & Kern in particular is a bona-fide audiophile source. Load 2 x 64GB cards atop the 32GB built-in memory and capacity is plenty stout.

My iMac instantly recognized Gato's USB input and streamed to it flawlessly. Meanwhile my Windows work machine threw conniption fits to even install the driver. Eventually it took only to stream with vinyl-type crackling in the background. After uninstalling prior drivers for AURALiC and Meitner, deleting and reinstalling Gato's once again accompanied by colorful curses until it took, I couldn't get XP Pro to recognize the DIA-250 as a selectable device even once.

Each time the amp powered up, Windows launched into the same tired tirade of 'your USB device has malfunctioned'. OSX had proven hardware happiness so Kresten Dinesen at Gato pegged it a software issue. With 200 units in the field they only had one prior incident on the books which got solved when the driver was reinstalled. In hoary tradition it fell to a reviewer to encounter an issue paying customers didn't. I thus skipped to the Wave 40 test. From my amp inventory of Bakoon AMP-12R, Crayon CFA-1.2, Goldmund/Job 225 and FirstWatt SIT1, the latter made for the most copasetic match with the widebanders. Hence that's what the DIA-250 replaced. Obviously I didn't expect matched sonics to $10.000/pr ultra-exotic 10wpc amps of single-stage single-ended zero NFB pedigree.

On Angelo Debarre's new Complicité album with virtuoso fiddler Marius Apostol, the fiery cymbalom of Kosty Lakatus makes an astonishing appearance on the title track. Impossibly fast notes whisk by with the instrument's trademark clattering metallic clangour. Here Gato's softer voicing shaved off some authentic edge. Ditto for the 24/192 purist recording of Rachel Podger performing Vivaldi's Violin Concertos with the Holland Baroque Society. Some insight into the very rich upper harmonics of the solo violin closed down. On David Orlowsky's soloizing [Jeremiah with the Singer Pure vocal ensemble interpreting Palestrina songs à la Garbarek/Hilliard's Officium] venue ambiance and the spidery decays in it were thus toned down to an equivalent extent.

In short the losses operated in a quite subtle domain, related somewhat to moving back a good number of rows in a live concert relative to the dominance of reflected sound incurred. Technically the baking class A amps—Blondie the cat is only good for about 10 minutes of sauna on them whilst moving them off the rack to just the floor by their heatsinks really toasts your fingers over just a few brief seconds—had more informative upper mid-to-treble coverage. That said the DIA-250's slightly darker reading was very compelling in its own right. Without this direct A/B I in fact doubt that most could relate to the term 'losses' above. Fed balanced straight off the Metrum Hex DAC, the DIA-250 was also perfectly ear-on-driver quiet. With its in this context overkill-squared power rating that was a bit of a shocker given how many even less powerful amps don't ace that.

If the peculiar gush factor of the tone wood speakers was slightly less so, this probably related directly to this amp's far lower output impedance. It likely overdamped Armin Galm's Envieé widebander a bit. On 'first-watt wakefulness' however I was truly and mightily impressed with the Dane. That it still won't be the ideal partner particularly on high-eff widebanders won't surprise anyone. That never was part of its design brief. This detour simply confirmed the prior desktop sighting. The DIA-250's 'torque' kicks in sooner than the DIA-400's. By contrast it's also the leaner more transparent operator and on tone very much in the potent but well-resolved push/pull valve realm.

On the close-captured hi-zoot Blue Grass of 3 Fervent Travelers' Time for Three with its scraping strings and smoking bows—or as IMG puts it, "the world's first classically trained garage band"—this avoids the kind of shrill strident glassy bits which two vigorously bowed violins on the wild side of the TV series Justified can exhibit. Gato's voicing thus steps back from the edge. As a result one suffers no encounters with flintiness. For the majority of listeners that's a perfect trade. On USB and my Windows PC, Kresten called it "a compatibility issue between the USB driver software and your system. There can be many reasons and I'm afraid I'm not able to pin it out for you." PureMusic's Rob Robinson or Emerald Physiks' Clayton Shaw had used TeamViewer log-on to remotely trouble-shoot or set up my Mac. Gato prefer not to.

"Usually we would have a distributor and/or retailer help our customers at this point out in the field. Accessing private computers even with permission raises a whole slew of security questions we don't want to begin considering. We don't want access to a customer's computer not because we can't but because we don't want the responsibility of handling private data, system stability etc." This is why I detest Microsoft's dependency on USB drivers for any and all 96kHz+ DACs. Apple's plug'n'play approach is so much easier if you're not a computer whiz to sort out this type of annoyance. Kresten: "I've been working most the day testing the USB driver trying to replicate the issues you've had. I turns out that our most recent driver version—the one you have—is more likely to have compatibility issues than the previous one. I'll be sending you an older version to install if you want to give it another go." Did I ever. I really wanted this to work. Alas no joy. I got the same prior 'if the device is connected already, unplug and replug it' circle jerk to never complete the device installation. "The only difference between the two drivers should be Win8 support. I could provoke sort of the same issues you have on a Win7 machine and solved it by installing the driver I sent. I've got one more driver to try." That sadly didn't even unzip all its elements properly to fail installation. Despite valiant efforts on Kresten's part, he finally conceded defeat from afar.

Conclusion. On sonics, features, looks and price—the total package as is—Gato's DIA-250 missed a well-deserved award by a mere whisker. Whilst I appreciate that some 200 customers had no issue, we just couldn't get my Windows machine to recognize the amp despite a properly installed driver. Predictably driver-less OSX happiness via USB was instant. Those can be the gremlins of computer audio. That aside, I found the smaller of the two Gatos to be quite the gâteau: yummy on all fronts, highly desirable and a fine specimen of intelligent integration, superb industrial design and a latest-gen class D implementation which further credits why this breed is not only here to stay but at least in the high-power sector predestined to dominate.

Postscript. A day after the above had published, my inner geek resurfaced. I'd had USB sound before, albeit with noise. Couldn't I at least get back to that? Vinyl hounds could live with such pops and crackles. So I spent two hours trying various things calm but determined. This included uninstalling a Thesycon program folder with 'drivers for XMOS-enabled devices' I found; re/uninstalling my various Gato drivers to hit upon the right one; trying a different USB cable; trying different USB ports; and possibly a little sumthin I don't remember or did by pure chance. Finally I saw the 'add hardware' wizard auto-launch itself after the nth re-installation of the above driver. I watched files being copied from the driver to the device without interruption or error messages. A short while later a 'your new USB device is ready for use' balloon popped up. Could it really be? My PC's clock said 23:47. Wizarding hour. I launched Spotify+. Voilà: 320kbps streaming without crackling. My inner geek grew a millimeter taller. Time to amend the above conclusion. With the annoying whisker removed (don't ask what I did) and just in time to see CNN confirm America's Oracle Team beat New Zealand's Emirates Team in a nail-biting conclusion to 2013's America's Cup, Gato's DIA-250 grabbed itself our Blue Moon Award. Well done*!

* I happily confess that these final two words include a smidgeon of self-pleased smugness...
Gato Audio website