Digital Processor Reviews

The EAD DSP-1000 III is housed in a 2.5" high, U-shaped chassis with a brushed-aluminum front panel. The cover is made of solid, 1/10"-thick steel with a nice "powder" finish, giving the unit an expensive feel. A pushbutton standby switch sitting below a green LED indicator sits at the panel's left. Even when set to Off, power is maintained for the decoder's circuits, but the digital inputs and analog outputs are muted. To the right, three pushbuttons allow selection of one of the three digital input sources (TosLink, 750 ohm coaxial, or glass optical interface). Like the EAD DSP-7000 unit reviewed by J. Gordon Holt and Steven Stone (Vol.18 Nos.1 & 5), the DSP-1000 accepts any of the three sampling rates: 32kHz, 44.1kHz, or 48kHz. Toward panel center is a lock light that illuminates when a digital data link is established. HDCD decoding occurs automatically whenever an HDCD disc is played, causing the front-panel HDCD indicator to light. No remote is available for this decoder.

UpTone Audio's USB Regen is a powered, single-port USB 2.0 hub that takes the USB signal from your computer, regenerates (ie, reclocks) the data, provides cleaned-up 5V power from a built-in, ultra–low-noise regulator, and sends an impedance-matched signal to your DAC. The Regen is designed to sit as close to your DAC as possible; UpTone supplies a male/male USB A/B adapter—a solid, double-ended plug, which they recommend over the 6"-long male/male USB A/B cable they also provide.

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.

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.

In hindsight, it was inevitable that two sophisticated digital audio technologies—software-based digital filters and Bitstream D/A converters—were destined to be married in one product. The software-based D/A converters offered by Krell, Wadia, and Theta all used multi-bit ladder DACs, and Bitstream-based units have previously relied on off-the-shelf digital filters.