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Reviewer: Srajan Ebaen
Financial Interests: click here
Source: 27" iMac with 3.4GHz quad-core Intel Core i7, 16GB 1.333MHz RAM, 2TB hard disc, 256GB SSD drive, ADM Radeon HD 6970M with 2GB of GDDR5 memory, OSX 10.8.2 Mountain Lion, PureMusic 1.88a in hybrid memory play with pre-allocated RAM and AIFF files up to 24/192; Audirvana 1.4.1; April Music Eximus DP1, Esoteric/APL Hifi UX1/NWO-M with Audiophilleo 2, Metrum Acoustics Hex [on review]
Preamp/Integrated: ModWright LS-100 with Synergy Hifi tubes, Esoteric C-03, Bent Audio Tap-X, TruLife Audio Athena
Amplifier: FirstWatt SIT1 & SIT2, ModWright KWA 100SE, Bakoon AMP-11R
Speakers: Aries Cerat Gladius, AudioSolutions Rhapsody 200
 Cables: Complete loom of Zu Audio Event, KingRex uArt USB cable with Bakoon BPS-02 battery supply
Stands: Artesania Esoteric twin 3-tier with optional glass table, Rajasthani hardwood amp rack
Powerline conditioning: GigaWatt PF2 on power amps, GigaWatt PC3-SE Evo on front end components
Sundry accessories: Extensive use of Acoustic System Resonators, noise filters and phase inverters
Room size: 5m x 11.5m W x D, 2.6m ceiling with exposed wooden cross beams every 60cm, plaster over brick walls, suspended wood floor with Tatami-type throw rugs. The listening space opens into the second storey via a staircase and the kitchen/dining room are behind the main listening chair. The latter is thus positioned in the middle of this open floor plan without the usual nearby back wall.
Review Component Retail: £6.900


The concept is literally sound, its byproduct ultra. The process of D/A conversion creates fold-back mirror images removed by the ubiquitous digital filters. Such temporal aliasing occurs above half of Redbook's sampling frequency, i.e. above 22.05kHz.


Upsampling 44.1kHz signal to ever higher frequencies upshifts this distortion. It parks earthly garbage in ultrasonic outer space where far gentler filter slopes than the original brickwall affairs are sufficient to clear out aliasing from the analog signal that's fed to your speakers. The contrarious non-over/upsampling concept dubbed NOS or zero-sampling was first proposed by Japanese thinker Ryohei Kusunoki, then popularized by 47 Laboratory. Champions in the top echelon include Zanden Audio, Abbingdon Music Research, Audio Note UK, Vertex AQ and Concert Fidelity but so-called NOS DACs are legion particularly in DIY.


The most popular chips for these vintage endeavors are the out-of-production Philips 1541 and 1543 R-2R ladder types though Cees Ruijtenberg of Metrum Acoustics uses silicon not from the usual audio vendors to pursue the same idea.
  
€2.371 Metrum Hex NOS converter with 16 paralleled chips, Lundahl output transformers for RCA and 24/192 asynchronous Cypress Semiconductor USB


This neatly segues into Scott Berry's 1543 DAC under the new Computer Audio Design banner. Like flying Dutchman Cees, this American Tektronix alumnus who divides his time between the UK and Chamonix/France multi-parallels chips until sixteen of his favored Philips TDA1543/N2 generate sufficient output voltage—1.65V or slightly below the industry-standard 2V—to eliminate a conventional active output stage. All that follow his Philips chips are a costly Duelund cap, an equally exotic resistor for passive I/V conversion and output transformers. Which begs the question. Why aside from self promotion would Mark Mallinson of Resonessence Labs have recently contributed 5 pages to Michael Lavorgna's Audiostream site explaining why modern DACs need digital filters?
Custom white casing with included Agora Acoustics MagicHexa™ viscoelastic polymer supports.
To be clear, Mallinson is perfectly correct. Clean measurements do require them. But it's equally correct to state that a number of modern DACs well regarded for their sonics don't bother with digital filters nor the very poor >22.05kHz measurements this entails. They consider those inaudible and irrelevant. They might say that the cure for these particular bad measurements is far worse than the—at least to them imaginary—disease. We'll leave the endless ensuing debate about the technical merits of such a decision to the engineers. Let's focus on why Scott Berry made it.
standard black casing with engraved identifiers
But first we shall exit the onset of measurement debatism with a quote from Martin Colloms' Hifi Critic review of the Metrum Octave NOS DAC: "... I checked the square wave claim and its phase is linear, with perfect square waves and no pre- or post ringing. Lacking digital signal processing, the usual replay filter ‘echo’ artefacts are absent, resulting in a very truthful and articulate sound... as previously found with other non-oversampled DACs, the spurious signals identified in the lab tests did not appear to affect the various items of hifi equipment that were used. Had this occurred, the sound quality could not have been as good..."


Summa summarum in triplicate: 1/ unfiltered aliasing noise didn't affect downstream gear; 2/ it wasn't audible either; 3/ the absence of digital filters created measurably superior impulse fidelity. Back to Scott Berry.
The casing's top is chemically bonded thick acrylic with 45° mitred joints which bolts to the base and rear panel.
7 October 2012 15:25. Hello Srajan, my name is Scott Berry. My wife Isabel and I have formed a new UK company called Computer Audio Design. We just released our first product, a USB-only non-oversampling DAC aimed at audiophiles who don't like the sound produced by most digital sources [emphasis mine - Ed]. My background was working as electrical engineer in R&D and manufacturing for high-tech industries, albeit not in audio. I am American and lived around Portland/Oregon for a long time before moving to the UK and meeting my British wife. Quite a few years ago I started making my own DACs to get the sound quality I liked. That's how it started. Not really having a history in audio development meant that our DAC could take an original approach - different materials and ideas which I feel give different results." 

 
Like Dennis Morecroft of DNM Design who has championed non-metallic audio enclosures for decades, Scott relies on thick matte-finished acrylic for his very plain black case. Custom colors are available but buyers will shoulder the extra cost for a complete sheet of other-than-black acrylic. His next crime is hardwiring the mains cord. Then follows a lack of power or any other switch for that matter. This is capped by a single asynchronous galvanically isolated USB input based on the Cypress Semiconductor transceiver like Antelope Audio uses in their Zodiac range; and a just as lonely single RCA output pair. This filthy rap sheet in audiophile criminology stands in crass contrast to goodie-two-shoe competitors with their endlessly selectable digital filters and socketry for all occasions. Busted. Handcuff time, perhaps some 1887 vintage Bean Giants? That's only half in jest. The 1543 DAC shackles you most severely and with great deliberation.