Description: Solid-state, mono power amplifier. Input: 1 balanced (XLR). Output: 2 pair custom, gold-plated binding posts. Input impedance, balanced (20Hz–20kHz): 10k ohms. Output impedance: 0.0075 ohm. Voltage gain: 31dB. Bandwidth: 0.3Hz–350kHz, –3dB. Input sensitivity: 592mV. Dynamic range: 110dB. THD+N: –110dB. Output power (at 1% THD+N, class-A): 55W into 8 ohms, 110W into 4 ohms, 220W into 2 ohms (all 17.4dBW). Power supply capacity: 440,000µFpc. Power consumption, high bias: <0.5W idle, 350W standby, 1350W maximum.
Dimensions: 18.5" (470mm) W × 9.…
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Sidebar 1: Specifications
Sidebar 2: Associated Equipment
Digital sources: dCS Rossini SACD/CD transport, Rossini DAC, and Rossini Clock; EMM Labs DV2 Integrated DAC; Synology 5-bay NAS 1019+; Roon Nucleus+ music server with HDPlex 200 linear power supply; Uptone Audio etherRegen, Small Green Computer Sonore opticalModule, TP-Link gigabit Ethernet media converters plus multimode duplex fiberoptic cable (2), Linksys routers (2); Small Green Computer linear power supply & Small Green Computer/ HDPlex four-component, 200W linear power supply (3); external hard drives, SSD USB sticks, iPad Pro; Apple 2017 Macbook…
Sidebar 3: Measurements
I tested the Gryphon Essence with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). I preconditioned the amplifier by operating it with class-AB output-stage bias at one-third the specified power into 8 ohms for an hour. At the end of that time, the top panel's temperature was 88.3°F (31.3°C) and that of the side-mounted heatsinks 90.4°F (32.4°C). Repeating the preconditioning with class-A bias after letting the amplifier cool down resulted in a slightly higher heatsink temperature, 92.1°F (33.4°C). The Essence monoblock easily has…
My, how we've grown! The experience that convinced me of the inevitability of streaming was in 2010 with the tiny, tidy Logitech Squeezebox Touch that, despite being discontinued and disowned by its manufacturer, still has a cult-like following. Since then, we have seen an explosion of devices for file playback from local or nonlocal storage and web streams. They have varied widely in size and price and wildly in their range of capabilities, from do-it-all feature sets with all system audio functions (save speakers) in one box, like the NAD M33, to daisy-chained, specialized components that…
From the Pink Faun via the Okto dac8 PRO, there was no system background noise, and the ambient aura before the music started mapped out a large space. The first notes surprised as they spilled out with requisite hall sound and body resonance from a large instrument that, only milliseconds before, was not there. Anyone who appreciates great piano playing will be hooked for the balance of the recital.
I also listened to one of my John Atkinson–engineered favorites, "The First Tears" by Eriks Eenvalds (The Doors of Heaven, Ethan Sperry, Portland State University Chamber Choir, Naxos 8.…
Sidebar 1: Specifications
Description: Custom, heavily optimized Linux-based digital music streamer/server running Roon core. Tested configuration: Base 2.16x plus USB bridge: $1250; S/PDIF bridge: $1250; Ultralow-noise OCXO clocks for motherboard, USB, and S/PDIF bridge: $1750 each; optional custom Lambo Orange anodized faceplate: $1000. Digital outputs (as equipped): Coaxial S/PDIF, XLR AES/EBU, USB I2S stereo/multichannel. Standard network connection on motherboard including gigabit LAN. Supported file formats: PCM, DSD. Supported sample rates: All PCM formats (limited only by DAC)…
Sidebar 2: Associated Equipment
Digital sources: Oppo Digital UDP-105 universal disc player, Baetis Prodigy X PC-based music server running JRiver Media Center v26 and Roon, exaSound Sigma streamer, Mytek Brooklyn, exaSound e38 Mark II and Okto dac8 PRO D/A processors. QNAP TVS-873 NAS.
Preamplifiers: Audio Research MP1, Coleman 7.1 Balanced Audio Switcher.
Power amplifiers: Benchmark AHB2, Classé Sigma Mono.
Loudspeakers: Revel Ultima2 Studio (L/C/R), Revel Performa3 F206 (SL/SR).
Cables: Digital: AudioQuest Coffee (USB). Interconnects: AudioQuest Earth/DBS balanced,…
For multichannel music fans, there is a fork in the road. You can take the well-traveled route based on readily available AVRs and preamp-processors intended for home theater. Or you can take the purist's route and face the challenge of finding a suitable and affordable multichannel DAC. Now that the $299, PCM-only miniDSP U-DAC8 has been withdrawn from the market, the least expensive multichannel DAC is the Merging Anubis at around $2000. That entry fee is a significant barrier for many.
For a couple of years, I have been following Prague-based Okto Research. At first, Pavel Krasensky,…
Sidebar 1: Specifications
Description: Eight-channel, digital-to-analog converter with volume control, 2 × 2.42" OLED display, 7 PCM reconstruction filters. Digital inputs: USB input and output, 8 AES/EBU. Outputs: 8 balanced (XLR) analog; headphone on ¼" stereo jack; stereo AES/EBU. PCM sample rates supported: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, and 192kHz via AES/EBU and USB. Maximum input word-length: up to 32 bits depending on input. Maximum output voltage at 0dBFS; 4.1V RMS at main and headphone outputs. Frequency response: not specified. Dynamic range: 125dB. THD+N: –119dB ref…
Sidebar 2: Measurements (from February 2021, Vol.44 No.2):
Kal Rubinson loaned me his 8-channel Okto dac8 PRO so I could compare its measured performance with that of the dac8 Stereo. From the front, the PRO looks identical to the Stereo. On the back, there are four AES/EBU inputs and one USB Type B port. Apple's USB Prober utility identified the multichannel DAC as "dac8PRO" from "Okto Research" with the serial number string "000032." The firmware version was 1.3. Like the dac8 Stereo, the PRO's USB port operated in the optimal isochronous asynchronous mode, and Apple's AudioMIDI utility…