Digital Processor Reviews

I got an early start on computer audio. At the end of the last century I was using WinAmp with first a CardDeluxe PCI soundcard, then a similar card from RME, to play files on a Windows PC. After I became a MacPerson, I used FireWire audio interfaces from pro-audio company Metric Halo and an inexpensive USB-connected ADC/DAC from M-Audio. But it was with the USB version of Benchmark's DAC 1 that the computer began taking over from physical discs for my music listening. At first I used iTunes au naturel, but as I acquired more high-resolution files, I began using Pure Music to handle all the tedious audio housekeeping, assigning as a dedicated music server a G4 Mac mini I'd bought in 2006.

The availability of the Pacific Microsonics High Definition Compatible Digital (HDCD®) PMD100 decoder chip, manufactured by San Jose's VLSI Technology, has brought about a minor revolution in Compact Disc playback. It brings sonic improvements in imaging, soundstaging, and resolution of detail. In the past six months, Stereophile has published a number of reports on the HDCD decoder's operation, what HDCD recordings are available, and the improvements brought by the HDCD chip to specific digital audio processors (footnote 1). High-end manufacturers are incorporating the $40 HDCD chip in their newest decoders, including the $4695 Sonic Frontiers SFD-2 Mk.II D/A processor, the $15,950 Mark Levinson No.30.5, and the $8195 Spectral SDR-2000 Professional HDCD D/A Processor (reviewed in Vol.18 No.5).

I've spent the last month recording songs for a pal's upcoming album. His act consists of powerful female and male singers, acoustic and electric bass, and acoustic guitars and mandolin. Jay-Z is funding the project, which is destined to transform the entire hip-hop/rap beat-driven pop landscape into an acoustic-music wonderland.

Okay, I jest about that last part.

Aurender was a name new to me when I encountered the company at the 2015 Consumer Electronics Show, where they displayed a range of music servers designed in California and manufactured in South Korea. But what caught my attention in Aurender's suite was their Flow portable D/A headphone amplifier ($1295). This handsome, battery-powered device, housed in a machined aluminum case about twice the size of a pack of playing cards, offers optical S/PDIF and USB 2.0/3.0 input ports and a single ¼" stereo headphone jack. Two features distinguish the Flow from the pack: Its USB input can be used with iOS (iPhone/iPad) and Android smartphone sources, and it can accept an mSATA drive (not included in price) of up to 1TB capacity for internal storage of audio files. Visually, the Flow's distinguishing feature is its round LCD display, which stands proud of the faceplate; the bezel encircling the display acts as a velocity-sensitive volume control operating in 0.5dB steps.

During my reviews of digital processors in the past year or so, I've made comparisons with the Wadia 2000 Digital Decoding Computer first reviewed by Arnis Balgalvis in Vol.13 No.1. I've felt that, as good as the 2000 is, other processors—many costing less than the 2000's $8500 price tag—are now superior.

However, a visiting Wadia representative looked inside our sample and used the word "ancient" to describe its circuitry in relation to current production. In addition, I was never able to audition the 2000 with a glass fiber-optical interface, standard equipment on Wadia's transports. Similarly, the $2000 Wadia X-32 had undergone a minor circuit revision, including the inclusion of the glass optical input. Consequently, a follow-up of these two excellent processors seemed in order.

A decade or two ago, I stumbled on a surprising demo room at an audio show. I don't recall most of the equipment, but I do remember a pair of Paradigm Studio 20 speakers at one end, their crossover entrails dangling free, connected to the rest of the system by a multiplicity of wires. At the other end, among the usual electronics, was a PC whose screen was a crazy quilt of graphs and menus that constantly twinkled in response to the ministrations of DEQX's Kim Ryrie. He seemed totally absorbed, but looked up and proudly offered to show me what he was doing. When I told him that I was familiar with the Paradigms, he played some music that sounded just fine. Then he clicked his mouse. The sound was transformed from the familiar to the fabulous. I was dumbfounded. "What have you done?"

There may have been a time when vacuum tubes and microprocessors seemed strange bedfellows. But nowadays—given the countless digital processors with tubed output stages, and an even greater number of tubed amps and preamps whose insides are crawling with the latest solid-state devices—we're more or less used to the idea. Here as elsewhere, hybrids are no big deal.